I think I may have found a solution for some of you.
I have a VIA HD Audio card, which is in reality a Realtek card because it uses a Realtek chipset or something like that.
Anyway, I've tried Realtek's and VIA's drivers
and none of them made a difference with the crackle/static/popping problem.
Then I decided to try the updated drivers on my PC manufacturer's site. I've had my computer on for 3 days straight, and haven't heard so much as a pop.
I uploaded the driver
I'm using so that you guys can try it out and see if it fixes your problem.
EDIT: Don't install it unless you are absolutely sure of what you are doing! Your computer most likely needs to have a Via chipset for this to actually work. MEGAUPLOAD - The leading online storage and file delivery service