If you've always wanted to know whether building a lightsaber was possible you've got to first understand how its actually built in the Star Wars stories. I cut and pasted the entire explanation over here so it'll be easier for you to read it.

From the Movies

The lightsaber is the weapon of a Jedi, an elegant armament of a more civilized time. In comparison, blasters are crude, inaccurate and loud affairs. To carry a lightsaber is an example of incredible skill and confidence, dexterity and attunement to the Force.

When deactivated, a lightsaber appears as a polished metallic handle, about 30 centimeters long, lined with control studs. At the press of a button the energy contained within is liberated and forms as a shaft of pure energy about a meter long. The saber hums and scintillates with a distinct sound. Its shimmering blade is capable of cutting through almost anything, save for the blade of another lightsaber.

In the hands of a Jedi, a lightsaber is almost unstoppable. It can be used to cut through blast doors or enemies alike. Using the Force, a Jedi can predict and deflect incoming blaster bolts, and reflect them back at the firer.

After the extermination of the Jedi ranks, lightsabers became rare relics. The knowledge of their construction disappeared with their masters. Luke Skywalker, the last of the Jedi, built his own lightsaber as the culmination of his training.

Although use of the lightsaber is strictly reserved to the Jedi -- the only ones capable of handling the difficult weapon -- it is also used by their sworn enemies, the Sith.

From the Expanded Universe

Lightsabers have changed little in the thousands of years of their employ by the Jedi Knights. Those who believe the Jedi order began on the ancient world of Ossus point to the abundance of Adegan crystals in the system as proof. These crystals are ideal for the creation of lightsabers, as they focus the energy released from a saber's power cell into the tight, blade-like beam. Early lightsabers did not have self-contained power cells, and were instead connected by a conducting cable to a belt-worn power pack.

Once unleashed, the power channels through a positively charged continuous energy lens at the center of the handle. The beam then arcs circumferentially back to a negatively charged high energy flux aperture. A superconductor transfers the power from the flux aperture to the power cell. As a result, a lightsaber only expends power when its blade cuts through something. So efficient is the blade, that it does not radiate heat unless it comes into contact with something.

The blade's color depends on the nature of the jewel it springs from, and while its length is fixed in the case of a single-jewel lightsaber, lightsabers equipped with multiple crystals can have their length varied by rotating a knob that allows the focusing crystal activator to subtly modify the refraction pattern between the gems.

With the Sith long believed extinct, lightsaber dueling occurred only within the practice chambers of the Jedi Temple. To a Jedi, a lightsaber is not just a weapon. It is a means of concentrating attention and becoming attuned with the Force.

Behind the Scenes

In the early incarnations of the Star Wars story, lightsabers were not weapons exclusive to the Jedi order. In fact, they were quite mundane, being used by Rebel and Imperial troopers alike. George Lucas then limited the weapon only to the Jedi Knights, to give the order a unique feel and an arcane quality.

The technique for realizing a lightsaber onscreen has varied throughout the years. In the pre-digital days of the original trilogy, a variety of methods were use to create the lightsaber effect both practically (on-set) and optically (during post-production).

One version had a motorized hilt that spun a blade covered in reflective material. The blade, when lit, did indeed glow in front of the camera, but it lacked the color and hazy corona that surrounded the pure white blade as seen in the finished film. These blades were cumbersome and fragile, and required a power source for the tiny motor. They did not make good sparring weapons, and the glow was colorless and inconsistent -- a tilt at the wrong angle would cause the blade to lose all its vibrancy from the camera's point of view.

Most of the lightsaber luminosity seen in the classic trilogy was the result of rotoscoping. Years ago, rotoscoping described the process of laying tracing paper over a blow-up of a film frame, and tracing, frame by frame, the necessary animation. This animation was typically painted onto an animation cel - a transparent sheet of acetate. Those cels would then be photographed one frame at a time, and optically composited into the frame.

The actors on set used simple rods that were colored in such a way as to make the job easier for the rotoscope artist. When a saber needed to be activated, one of two methods was used. A simple editing trick stopped the camera so that a prop man could replaced an unlit saber (which is just a handle) with a lit saber (one with a blade attached). When the film was played back, the saber blade would magically appear. The other method involved the actor using an unlit blade throughout, and the rotoscope artist would draw the growing blade. Since correctly drawing in the glowing blade without the benefit of a prop blade as reference is a challenging task, the scenes where a saber is first activated usually cuts away, to allow the replacement of the unlit prop with a full-bladed weapon.

Answer: First of all, when lasers are fired they kind of never stop. So unless you're looking to have a lightsaber that's travelling 100,000s of miles then whoopee, easily done. However, if you want to be able to duel with your enemy using this one its easier to just fire on them with a laser gun. Now, having read that, we know that there are no such gems on Earth, (or at least none that we have discovered yet), so we couldn't do it that way.  But, laser technology is so advanced that we could produce one with a laser.  Lasers can now be focused into so much heat, that one could cut through virtually anything much like one could with a Star Wars lightsaber.  The only problem is this:  as of right now, all lasers that are that powerful, are infinite lines of light/heat.  One could not harness it into a small enough beam to be of a lightsaber's length:  it would either be that length and have no real power, or it would be a whole lot longer than that and have immense amounts of power.  With how quick laser technology is advancing though, it may be possible very soon to concentrate it into a beam the length of a lightsaber without it losing any power.

The brochure of the hyperdrive travels would probably have what you can find on the star wars galaxy website:

Travel between star systems would be impossible were it not for the development of the revolutionary hyperdrive propulsion system. The term hyperdrive refers to the engine and interrelated systems that propel a starship through the alternate dimension of hyperspace. In hyperspace, there is no limit to how fast a starship can travel, and thus interstellar distances can be traversed in mere minutes.

Before entering hyperspace, a pilot must supply exact coordinates derived by the ship's navicomputer. Without precise calculations, a ship may collide with a body in hyperspace with catastrophic results.

Although largely reliable, constant modifications to a hyperdrive can render it untrustworthy. Han Solo's Millennium Falcon had an extremely recalcitrant hyperdrive which often failed when needed the most.

Nice indeed. But how possible is this and how far away are we from this technology?

We come as close as possible with this technology that the chinese are creating.

From the Star Wars site:

The Death Star was the code name of an unspeakably powerful and horrific weapon developed by the Empire. The immense space station carried a weapon capable of destroying entire planets. The Death Star was to be an instrument of terror, meant to cow treasonous worlds with the threat of annihilation. While the massive station is evidence of the evil that was the Galactic Empire, it was also proof of the New Order's greatest weakness -- the belief that technology and terror were superior to the will of oppressed beings fighting for freedom.

The Death Star was a battle station the size of a small moon. It had a formidable array of turbolasers and tractor beam projectors, giving it the firepower of greater than half the Imperial starfleet. Within its cavernous interior were legions of Imperial troops and fightercraft, as well as all manner of detention blocks and interrogation cells. The Death Star was spherical, and dark gray in color. Located on the Death Star's northern hemisphere was a concave disk housing the station's main laser weapon.

The technical schematics for the Death Star were developed by the cutting edge technologists of the Confederacy of Independent Systems during the Clone Wars. With the defeat of the Separatists and the Republic's transformation into Empire, the Death Star project fell under the command of Grand Moff Tarkin, one the Empire's preeminent governors. The Death Star was developed in secret, through many difficulties over a span of almost 20 years. Rebel Alliance spies were nonetheless able to learn of the weapon's existence, and stole vital technical schematics from guarded Imperial vaults. These desperate spies transmitted this data to Rebel leader Princess Leia Organa, who stored the plans in R2-D2's memory systems. 

It would seem that this is almost impossible considering the amount of energy required to blow up an entire planet. It may even be impssible to begin why this entire thing is seriously not worth talking about. Just don't let the terrorists get their hands on the blue prints!\

via Star Wars