It does work on XP, but better with vista. Yes windows 7 does support it and it works fine, remember windows 7 is actually just windows vista which has been top fixed for many issues and then a new layout
Microsoft is pretty much like Blizzard, releasing things that aint finish and then fix it from time to time
There is missing one funktion the "show windows side by side" funktion, but if your useing keyclone that great software can do it for you

/Selz