The supplied driver from Intel in the Download Center site works just fine under Windows 7 x64 in my personal experience. I have both on-board sound, and an add-on ESI Juli@ card in my system, and both work exactly as expected.
The only time I have seen problems with the on-board sound is when I was occasionally getting no output from digital out, and that was finally resolved unchecking "Exclusive Mode" settings in the device properties.
works fine with me too. you should check every piece of software you installed after the operating system, and undo anything you did to the biossettings for a try.