it's a myspace-thing. they re-encode the audio, so you can't really do anything about it.
but you could optimize your file for it. try to cut the high frequencies of your audio. only as much that it's not audible yet. this may reduce artifacts, which appear when the encoder is cutting the inaudible (high) frequencies of the audio to reduce data.

never tried it myself, though. let me know if it worked.

I tried rolling off the highs at 12k without any noticeable difference, I even tried bouncing to MP3 at 128kb/s thinking that my usual bounce at 320 would have to be chopped into smaller pieces and thus have "holes," and even that didn't work. Sheesh, there really is no site that will let you stream uncompressed files is there?

Soundclick.com lets you do 128kbps...(if you pay, you get 320)
Try 96kbps, perhaps myspace won't convert those.

I've signed up for like 4 sites already and don't use them because I don't want my files to be downloadable, but they don't say whether or not they are until you post something and/or they stream in bad quality. Are soundclick files downloadable? Will I be able to link directly to the file so people don't have to click 4 times to hear something I've done? because I still haven't found one site to do all that short of making my own site v_v (sigh)

"Are soundclick files downloadable?"
Your choice.

You can link directly to a player which minimises it to 2 clicks (one is a play button, one is to launch the player).
I think it auto-plays actually so that means 1 click.