Computer interferance-how close is too close?

Theory is not the issue. Can YOU hear any problems?
If not, don't worry about it.

The computer and monitor that I use to digitize my vinyl and stream stations from the Internet sits in the same cabinet as and directly below my amp and CDP. As long as the monitor is asleep, things are fine at low volume. However, if I turn up the volume, there is audible static and hum when I use the CDP or TT. When I want to crank it, I shut down the computer and turn off the monitor, and there is blissful silence...

I get lines on my TV when my PC is on, even though it is about 20 feet away.

One suggestion might be to place a cotton cloth (towel?) between the PC and the audio equipment. Cotton has great RFI limiting qualities and it is cheap.