Ok, weird problem here - I've got a Creative X-Fi XtremeMusic and Windows 7 will detect it, and I've installed the latest drivers
When it first installs, things are fine. I get sound through iTunes and System sounds.
But after the first reboot, it hisses and crackles and pops.
If I go Control Panel -> Hardware & Sound -> Manage Audio Devices, hit configure and try to run the little sound test, it usually hangs and doesn't even get through the test.
I've tried turning of EAX Effects, CMSS, etc and nothing seems to change it.