Altec Lansing GCS100 speakers

Welcome to the wonderful world of electricity. You have at least three choices: You can spend an unknown (and possibly extended) amount of time and effort shielding this, grounding that, and generally guessing and tinkering at what might be causing the interference, or you can unplug the speakers (you might have to unplug the power supply, or possibly just the connection to the PC) when the system is not in use. After all, if the PC is shut down, you don't need them at that point anyway. There's no telling what might be causing this, nor is it necessarily an easy thing to fix. If you have the speaker power supply plugged into the same surge suppressor as the PC, isolating the power source (i.e., plugging it in somewhere else) might do the trick. Then again, it might not.

One other option might be to just get some contemporary speakers for the new system.

Thanks for the reply. I'll try plugging the speakers into a different source, then I'll buy new ones like I should have when I bought the system.