Crackling Audio STAC9750

I have a Dell 700m. A few weeks ago, I decided to reformat and reinstall Windows after a few computing mishaps. I first downloaded all the drivers from Dell's website in preparation. After the installation of Windows, audio seemed to be working fine.

I then did two things after that (I think). I updated my optical drives firmware and I installed some SpeedStep fix. Both were things that Dell provided. I then started hearing crackling and skips in audio. I immediately thought it was SpeedStep, so I read that turning my computer's Power settings to "Always On" would disable it. By monitoring my CPU with mobmeter, I noticed that this did bump my CPU output from 800 mhz back to its max of 1.6. This stopped a lot of the crackling, but did not eliminate it.

So then I reformatted and reinstalled Windows again because I figured "Hey, I just did it, so it's not like I'll lose anything." But this time I did not install the SpeedStep fix. But it's still crackling. I thought SpeedStep was just some registry thing, but maybe it did more than that underneath the OS layer.

Weird thing: I've tested out playing audio, and sometimes after a reboot it doesn't get crackly until CPU usage goes up, and then it stays crackly for the rest of the Windows session.

Another weird thing: Sound from DVDs works perfectly and sounds great. And sometimes after playing a DVD, I can go back and try audio from another program and it is not crackly when it normally would have been.

So, in short, the differences from before I initially installed:

BEFORE:
Windows XP Pro SP2

AFTER:
Windows XP Home SP3
Intel SpeedStep fix
optical drive firmware update

I've also included an EVEREST summary just in case anyone would like to see it.

Thank you for any help.