well, myspace quality is shite, so I wouldn`t worry about that, youtube however, the only solution is to upload naff quality.
However it`s like trying to hold back the tide with a teaspoon.
Vinyl, WAV whatever it is online and available to the unscrupulous within a day, no matter what you do.
So I would say foget it, keep the quality up so people can here it properly, and those that want to pay will pay.