If you go into the Windows device manager (Open Start, type devmgmt.msc and press enter), is there a yellow triangle symbol on the sound card?
(might indicate an IRQ or base address problem)
Can you check the chip on the sound card to make
sure it's a CMI8738 (written on the chip itself)
See if there is anything on here that helps:
http://www.sevenforums.com/sound-audio/ ... i8738.html
I'm amazed that Win7 has issues with CMI8738 chips, as they were one of the most common generic sound chips.
Some people say the WinXP drivers work...
I'll dig out a CMI8738 based card tonight, and see if I have any probs with Win7... other than the fact that it's Windows
[EDIT]
Sorry I couldn't find a CMI8738 based card, but I'll see if I've got one at work, and get back to you.