I have vista and as in my other posts regarding music on the zumo I use noteburner to convert my music files to mp3, i then use mp3 gain to normalise them.
I remove my sd card from the zumo and use a card reader to transfer my mp3's to the sd card. The zumo can use cards up to 4gb, anything bigger and it wont see the tracks (something to do with when the zumo came out the largest card was 4gb) i think???
Another tip is to have 1 folder on the card named mp3 and then within that set up a folder for each album or playlist, the zumo will boot quicker that way.
Read my other post
here and lots of zumo info
here
Biker