Slow boot time in Vista x64

I just built a new computer with an Intel Q6600 on an Intel P33/34 based board with 4gb of RAM.

I first installed Vista Home Premium 32 bit and it worked just fine, booted very fast. I then formatted the drive and installed Vista Ultimate x64. However, every time I boot (from the first boot until my most recent) it takes forever to load. The hang-up comes on the copyright screen, when the green progress bar goes from left to right. It sits at this screen for more than 2 minutes. The bar continuously goes from left to right non-stop, there's no freezing or hiccoughing. It...just...loads...slow. And I noticed that right after this is done, I see the old fashioned mouse cursor (a la XP) and I see it slowly change to the shortened tail of the Vista cursor. Once the Windows logo finally appears, the computer then begins running at what I consider a normal acceptable speed.

I've re-installed the OS, I've tried booting into Safe Mode, each time I am inflicted with this slow boot time. But whenever I boot into a 32 bit OS, there is no delay at all.

I've searched all over and I haven't found anyone who's had a similar problem. I'm thinking there's something driver-related. I checked my Event Log and don't notice anything out of the ordinary.

I know it's a stretch, but has anyone else seen or heard of this issue?

Thanks.