I recommend XWvT... (for multiplayer, and for oldscoolness)
XWAUP is interesting (and an improvment on XWA), there is also the Darksaber patch and you can tweak the game using a GUI editor (and edit the text files to make capital ships 'playable'). IMHO, XWA multiplayer is limited to dogfights, but there were some quite good single player campaigns (I recall one where you're a pirate).