u can put any music on ur ipod that is AAC (16 to 320 Kbps), Protected AAC (from iTunes Music Store), MP3 (16 to 320 Kbps), MP3 VBR, Audible (formats 2, 3 and 4), Apple Lossless, WAV, AIFF. of course downloading music from other computers is illegal but u can do wat u want to do.
www.apple.com