2.2 Edition for me, with a modified timeline and character generation.
Hey Jawa, you can either get the CD-ROMs as Stainless mentions which are a great deal, or if you only need a few you can get individual PDFs from DriveThruRPG.com, will work out more expensive overall if you want all the books, but good for filling in gaps if you need to.
http://www.drivethrurpg.com/browse/p.../Twilight-2000