From most of the digital audio player forums I've been in, a very popular setup is ripping with
Exact Audio Copy (EAC) and encoding with the
LAME mp3 encoder at
alt-preset quality. This results in very high quality VBR (variable bit rate) mp3's that play on EVERY mp3 player, as well as the Axim.
OGG Vorbis/ is also quite popular and uses half the space as mp3; however, it is not as portable and uses more power. For example, you won't be able to play your .OGG music on an iPod in the future.
alan