ok....
so you tried unplugging the monitor??
and the speakers??
other than that.. do you have any wireless devices on your computer?? mouse, keyboard, lan,
You could also try this......
get ahold any CB buddies or ham radio buddies you may have.... Ask around you would be suprised... See if they have a RF meter that they could bring over and see if they can find any sources of RF coming off the pc that varies from win2k and linux.... Ham radio operators are normally pretty good at this kind of stuff, because they care about what their equipment does to others.......
another option... replace the CAT and the CAT door... LOL