So about a week ago I upgraded my motherboard, processor, and RAM. Prior to this I had already bought a EVGA 8800GTX, and had tried multiple times to upgrade (downgrade?) to Vista. I could usually get the system up and running, but due to some sort of driver issue my system would often time out while accessing my hard drives. No biggie, my chipset wasn't really designed for Vista anyway.

I also had a strange issue while playing modern games like Bioshock and Crysis; after about 30-40 minutes of playing, the game would freeze, the sound would loop continuously, and after about 10 seconds my monitor would lose the signal to the video card. No amount of fancy keyboard combinations would cause my computer to snap out of it, I had to hold down the power button to reset it. Increasing the fan speed on my video card would usually extend the amount of time I could play before freezing, but it never was completely fixed. I went back to Windows XP and never had another issue; aside from the occasional game freezing due to having not turned off my computer for days at a time.

Fast forward to this week, where I have shiny new hardware that runs without a hitch on Vista. Except for one thing. I still get the sound loop/no signal freeze. I have the latest drivers, and I downloaded Service Pack 1 and all available Vista hotfixes. I haven't really played much Bioshock or Crysis lately, but I've definitely been on TF2 a lot, and unfortunately the crash also happens in TF2. I'm almost positive this is a software issue, because this never happens in XP or Linux, and the card would be displaying different symptoms if it was overheating. And I don't really want to have to go back and reinstall XP, because there are certain features of the hardware that are only available in Vista.

I've searched the internet for solutions, and it appears that this is a fairly common issue, though no one yet really seems to have a working solution.

Yeah, but this thing can operate safely up to 80 degrees celsius. The warmest I've ever seen it get was 79, and that was while running ATI Tool to intentionally stress test it. I had hoped that by purchasing a Thermaltake Armor VA8000BWS that heat and airflow would never be a problem.

If it is a heat problem, I'd like to punch the Microsoft programmer responsible for making my computer overheat.

Slow down some. You provided waaay too much information and left some important things out.
First of all list your hardware(mb/ram/videocard). Next what are your cpu/gpu temps?
Please explain what you call the loop/no signal freeze. You mean the game locks up and the audio loops?

The card idles at 57 C, which I assume to be normal. It only gets up to 70 most of the time, 79 if I intentionally stress the hell out of it.

I've considered getting one of those. I like how it's cheaper than the famous Thermalright HR-03 and even does a better job at keeping it cool.

Sound card drivers are up to date, so if it's a sound issue there probably isn't a fix.

So far I've been able to avoid crashing by turning up the fan speed on my GPU, and that seemed to work perfectly yesterday. But I also didn't play TF2 for more than about an hour and a half at a time, so the issue may still be present.

Get over the Vista and video card issues folks.  Drivers are now mature enough.  I have run Vista for a year and never had any issues and I have an 8800 card.

Vista does utilize your memory better and uses more of it to improve performance.  I still think it is a heat issue.

Yeah ok. lol  Nevermind that I work on these systems every single day and see these problems repeatedly. Please don't start another "Vista is king" debate.
I'm not dissing vista so just cool your jets. Yes vista does still have issues but it doesn't have near the support and roots that xp does so this is to be expected. It took xp a good few years to become "very stable" and it will be the same for vista(or windows 7 as it will be known).

Not exactly but assuming this is happening outside the OS and not just in a windows environment  I would immediately start checking cables & jumper settings.