Random Freezing

I got a copy of Vista Ultimate at the recent Launch Event. I purchased
a new 500Gb SATA drive to install it on. Everything went fine during
the installation, but after startup, the machine will freeze
completely. At first I was rebooting, but finally I decided to wait.
The machine comes back to life after about 5-6 minutes. The clock is
5-6 minutes off after it comes back, so I guess that even the OS
doesn't know why it's freezing.

I've seen that other people have had many issues with Vista freezing,
but I haven't seen much in the way of solutions. My plan is to
disconnect all unnecessary hardware and see if I still have the
problem. If not, I'll add back one piece of hardware at a time to find
the culprit. If I still have the problem after removing all the
hardware, I'm out of options short of a complete re-install.

Any ideas?