My wacky sound card

For some reason, recently, my sound card on my speak started doing an odd thing. One speaker plays all the sounds, music, whatever sound the computer tells it to. The other one, however, plays static which it gets from the inside of my computer, and it always plays it. That must sound confusing, let me explain, when I am doing something hard drive intensive, (my hard drive is noisy), I notice the sound inside the computer (sometimes I just take off the case and let my computer hang out :)) and I hear the same noise coming from the speaker. This is somewhat recent, a problem I only came across a few months ago. I guess it is my sound card, but does anyone have any suggestions?

did you recently get a second hard drive or replace one that you previously had?
i once owner a quantam bigfoot (a tank of a drive and very ancient i know) and whenever that tried to read or write (it was a 2nd drive) it would cause distortion on the sound card and speakers, with 1 hard drive it was fine

im not sure what causes it exactly but ive heard rumours it may be magnetic interference or insufficient sheilding on the speakers you use?