The Dragonstar campaign is easily one of my favorite settings of all time. The main rules use the D20 3.0 rules set but are quite easy to convert over to 3.5. All of the core races from the PH are available, plus several new additions: Drow, Orcs, Half-Dragons, and Soulmechs. The standard classes are all there as well, plus new classes the Pilot and Mechanist.
Bringing D&D into space has been handled smoothly and easily, and the game opens up worlds of possibilities for the DM and players. I highly recommend picking up this and the Guide to the Galaxy.
[5 of 5 Stars!]