Sound is horrible after reinstalling Vista Ultimate

Ok, so I don't know exactly which topic this should be under, but I think it is a software and not a hardware problem.

I recently reinstalled Vista Ultimate 64 on my computer and my sound is horrible; constantly making cracking noises. It is definetly not my speakers bkz I hooked them into my macbook and they sound great. The crackling is in all programs (IE7, iTunes, WMP) and gets worse if I am doing something, such as clicking on a link, scrolling in a webpage or opening a program. All drivers are downloaded and current. Here are my specs. Please help..
BTW the speakers are USB and not a an audio output, though I did try using audio output and had the same results.


Bose Companion 5 Speakers
Q6700
4gb Patriot Extreme 800mhz ram
Gigabyte P35-DQ6
2x 400gb HDD

Thanks in advanced.

Dave