You have to re-learn evrything you thought you knew with Vista, once you have you'll never want to go back!
As others have already suggested, turn the UAC off to begin with and make sure you run everything as an Administrator, this isn't default, you have to tell it!
You may even have to make sure all permissions are set to full as well!
I gotta say though that seeing as you went for a Quad 6600 you should have gone 64 bit as well because that's where it's all going now, 32 bit is a dying breed!!

I use Vista Ultimate 64 and would never go back to xp now!

Injustice will be avenged.
Cofiwch Dryweryn.