Music files are mosly mp3 and these can be loaded onto iPod no problem. There are problems with some file types, but they are types you will probably never come across.
I used one other make of player for a short time, and whilst it would play Limewire downloads it would not play purchased music, so personally I stick with iPod.
but I am biased to Apple
The following link should help
http://www.gnutellaforums.com/showth...threadid=36230