Well, its only a guess, but since word has it that XP outperforms the 32 bit vistas, and vista premium 64 outperformed XP for me, I think you'll benefit.
In fact, if my experience is anything to go by, you'll benefit a lot.
There are a small handfull of things that it doesnt get on with (virgin speedtouch modems and SX3 are the only ones of any cosequence that were pertinent to me - I forgot about the modem before - but one router and a plan for sonar 7 later and all is well!)
Its running 3 and 4 year old software that I couldnt find anything on and chanced without any problem.
And did I mention its fast? Like FAST. My Emu patchmix loads about 10 times faster (no exageration) than on XP, for example. No idea why: its a 32 bit app, but even 32 bit apps are faster. Crysis (I couldnt resist giving it a whirl with DX10) runs faster than before, with higher settings, Foobar2000, my audio player of choice, loads my 12000 songs at least 3 times faster. VLC plays vids nearly immediately (rather than making me wait a whole 4 or 5 seconds: I just couldnt take that any more :lol: )
And so on.
Like I say, bar SX3 and the modem its much, much better (faster/more stable). I have no idea why poeple dont like it. Maybe 32bit vista really is a dog, but this is great.
