Ground loops in VGA connection to TV?

[N2IXK]

Is there anyone here who has dealt with ground loops in computer display systems? I recently added a connection between the VGA input of my Sony LCD TV and my PC, and it works, but there is a 60 Hz buzz in the audio and a hum bar rolling through the picture.

Temporarily lifting the AC power ground at the PC clears it up, but obviously that isn't a safe permanent fix. The PC and the TV are already on the same branch circuit. Everything works fine when testing with a laptop (on battery), but plugging the laptop into AC brings the hum back, as well.

The connection between the TV and PC consists of 2 cables, a 15 pin VGA cable and a 1/8" stereo audio cable. An isolation transformer for the audio link is easily available for a few bucks, and has already been ordered. A suitable VGA isolator seems a LOT harder to find. I only seem to find ONE manufacturer of such a device, at a cost of ~$140:

http://www.markertek.com/Video-Equip...T-VGA11S.xhtml

Before I drop the money for one of these, I would like to be SURE that it is going to clear things up. Has anyone used one of these gadgets successfully, or found a cheaper solution to this problem?