I've had XvT and XWA working on my computer, which is running Win 7 64 bit. Not easy, and I had to do some research but posted everything here:
http://forums.fsmod.com/viewtopic.php?id=9584
As far as online playing gos, I only know of two clubs still playing it online, TRA and TFA. They can be found at www.darkjedi.org
I believe they use some form of matchmaking service called voobly. Just google voobly, then go make an account with it. I couldn't get it working online, kept timing out. With some of these older games there are a lot of issues with setting up port forwarding or setting router to DMZ etc. Someone from the clubs will no doubt be in voobly though and will be able to help you out.
Good luck.
Bite my shiny metal Tie Fighter!

