Hey, first of all...
@ Maggot
I had a similar problem with my old intergrated AC 97, it just stopped to produce sound on my left speaker - there was some sound, but it was so quiet that you could barely make out what it was...
Right speaker was loud as normal, although the volume was set to same for both speaker...
After a while I gave up and bought a SB Live!...
The only thing you could check is the mixer - if everything seems alright, the jack is probably faulty... then you could RMA the board (not recommended as it'll take time) or go to the nearest shop and buy a cheap but good sound card (SB Live! is really cheap now, and it still aint that bad, better than AC 97 for sure).
@Chosen Angel
The thing is, AC 97' relies on software decoding instead of hardware, so your CPU is being loaded to process the sound. However, when playing , the CPU is given much more intensive and important tasks such as managing AI, physics, some geometry calculations and etc. So with a non-hardware sound solution you should expect the occasional sound stuttering.
About the 'white' Chief, its actually missing textures, or they are not being applied correctly - with an intergrated card you will have these kind of problems, partly cause their drivers suck, and partly because they dont have enough memory (you could try to assign more memory to the card). For 140-150$ you could get a really good card (many times better,faster, with no problems) compared to the intergrated POS... If you need a suggestion which one, just ask.