As I'm running windows vista enterprise edition, i can say with delight that free space 2 works just fine.
Even with all the mods, so does source, even though you need to start it with admin privileges (you can set it by right clicking the shortcut / exe and then selecting run as administrator)
In fact, the only problem iv had with windows vista is, if you install the latest AC97 sound card drivers, it crashes windows explorer when trying to open Control panel.
want me to get you a screen shot of free space2 running in vista in windows mode? with fps counter?