get one of those FM transmitters that plug into the cig lighter. They sell them at Wal-mart. Use a retractable hotsync cable to keep your 600/650/700 charged.

They also sell a version that plays WMA's. You could also just use a USB card reader and pull your card out of the Treo.

http://www.walmart.com/catalog/produ...uct_id=3579125