Home made audio isolation transformer?

I hooked up my father's PC to the entertainment system so we can watch movies on the big screen TV but the audio picks up an very annoying buzz. My father says it is caused by a creeping ground current between the computer system and the entertainment system and has suggested using an isolation transformer to solve the problem.

For the moment obtaining one commercially is somewhat difficult because we keep forgetting to go pick one up. (It's not a priority) and also because we are not aware of any local stores that carry such a device.

Anyway, long story short I wound up attemping to make a similar device using a thin iron nail and some extremely small insolated wire. I estimate that there are approximately 150 loops of wire however it may be much higher. During a test it reproduced the sound from my Sony MD perfectly on my headphones.

(I'm writing this very late so I havent had a chance to see if they solve the noise problem) However, if I were to use it on my entertainment system are there any problems I might encounter? Would the load it provides be too weak and eventually burn out the computers sound card, for example?

FYI, the cables I use to connect the PC to the system are regular coaxial cable with RCA component tips. I made them myself since we didnt have any 25 foot cables.

Also, if the isolation transformer route is a totally wrong approach what are your suggestions?

My only concern about this would be durability; you'll want to have some way of keeping the homemade transformer from unravelling itself. Also, you'll need one per channel (left and right). As for load, at line levels it shouldn't be a problem. (Also, you'll want to make sure both sides of the transformer have the same number of turns, since isolation transformers are supposed to be 1:1. 150 should be more than enough.)

If you're not all that keen on going to the trouble of building one, and you're in the US, Radio Shack sells a "ground loop isolator" (basically the same thing) that works pretty well.