100% core utilization in vista

I recently built a new computer and decided to try out vista (LOL FAG). I obtained an OEM copy from a tech shop in town, and ever since I've installed it, one of the cores in my athlon fx2 6000+ is always at 100% utilization. even sitting on desktop with no services running besides the default windows ones, it's always maxed out. I have all available drivers and updates for windows and my hardware, and microsoft is of no help since this computer isn't a dell or HP system. Anybody got any ideas as to why this is happening, or how I could fix it?

Never tried Vista.  Keep hearing it really sucks.  What the hell is supposed to be so great about it that'll make me want to leave XP?  (Or win 95 for that matter)