Computer interferance-how close is too close?

Hi. I have limited space, and am currently housing my C-J PV10A preamp and Rotel CD Player about 1.5 feet from my computer monitor, and about 3 feet from my CPU. Is this acceptable, or am I producing interfernace that will cause poor reproduction?
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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.

It just seems to depend. We have a PC that we're using as a multi-media server located right next to the equipment rack. No problems whatsoever. Same when we line-in our laptops for MP3 playback. On the other hand, when our neighbor places his laptop near his amp, it buzzes like a fridge.

I think it has a lot to do with the case the machine's in. El Cheapo PC's and monitors use cheap cases with poor shielding. Better towers/CRT's SHOULD have better shielding.

Ultimately, Elizabeth is right. If you can't hear/see any interferance, you should be fine.

Pbowne, I'm wondering if you might have some household wiring issues. I've never heard of a PC creating THAT much interferance. It shouldn't, at any rate...