[update]I forgot to mention this is on Windows XP x64.[/update] 

I'm still experiencing some random hangs on my rebuilt machine every couple of hours or so and have finally decided to get off my lazy rear end and track down why it's happening.  I'm 90% sure it's related to my sound card driver, but of course cannot be positive.  So I've configured my machine to generate crash dumps, have downloaded all of the necessary diagnostic tools (WinDbg, symbol files, etc) for looking at said crash dumps...

And the damn machine hasn't crashed in 24 hours.

This is the first consecutive 24 hours I've experienced since I rebuilt the thing a week ago.  Not that I want it to crash, but now that I'm prepared to get to the root of it, everything is behaving as expected.

I've found the same paradigm to be true when debugging production applications...they only misbehave when you aren't looking (you should of course have tracing/logging built into your applications, but that's beside the point).  As soon as you threaten them with a debugger they shape up and behave normally.

*sigh*