Umm, well,
www.starwars.nu is developed and doesnt look like an official site looking at the bottom of the page so you should be okay.
If its a fan-site you should be okay, if you are selling Star Wars merchandise they would probably have a word.
If you build it around missles and Space Stations and dont mention the film, you have no problem at all.
Furthermore, starwars.net (!) and starwars.biz isnt owned by Lucasfilms, though its not developed.
Give the .net owner a call and ask if he was ever contacted about the name by Lucasfilms. Its strange that it was never developed unless the owner had the same concerns.
It was a boring war related site in 1998, a pest-control site in 1997 and a personal homepage in 1996 when it was first registered.
If you want to stay on the safe ground and fancy developing it , you could turn it into either a celeb porn site or a site which gossips about 'Stars' and airs their grievances with other celebs and the media. Maybe even a site having a pop at celebrities in a humorous way.