System audio files appearing in playlist
Add a blank file named .nomedia in the folders containing music that you don't want to be seen in the music player. Media scanner ignores files in the folder with .nomedia file. I have never tried this on Eclair, but I guess it should work.

And yes, you may have to restart the device after this is done.

EDIT:

The restart is to trigger the Media Scanner to do its job. You can also trigger it by unmounting and remounting your SD card (which can be done from Storage Settings or by connecting it to your computer), or by using one of the "trigger-happy-apps" like e.g. SDrescan