AM radio noise

I've had this problem awhile but it seemed to be getting worse. My
computer pretty much wipes out my AM radio (FM unaffected). All the
wall sockets in my room are on the same circuit so I'm out of luck
moving the radio. Now... I expect the AM radio to go bonkers if the
system is on but this happens when the computer is off too. If I
switch the power supply to off in the back of the case all is well. Is
this normal?

The graphics board always has a light on (Radian 9600 pro) for the 8x
agp but I wouldn't think this would have that kind of affect. I hooked
the computer up to a belkin surgemaster with a high frequency
capacitor to no avail. I hooked my AM radio to the same surge
protector and again zippo.

Could the power supply be the culprit? If so are there ones on the
market anyone could recommend that wouldn't contaminate the AC line of
the house?

Thanks

Randy