I have the C-Media AC97 onboard audio and it works perfectly. Using driver version 5.12.1.49. I also have Creative Audigy 4 Pro on this computer and even using the driver advised on this forum, it is crap! It works but produces distortion intermittently, the onboard sound doesn't have any issues.
One point of interest is that at work I installed Windows 7 on a computer that doesn't even have Vista drivers for it. It's an IBM M50 using Intel chipset. I downloaded the XP drivers for the graphics and audio, ran them in compatibility mode and both work perfectly!