Hotsync em. If you have Sprint service your phone came with a Sprint software to manage your music. You can use your HotSync to transfer songs already on your pc to your phone. Or you can use a program called Card Reader for palm. Its a program that turns your pc into a Usb Storage unit. You have to have hotsync cable plugged in to use this. You connect your hotsync cable...turn this program on...it pops up a popup window (if your on Vista, not sure about any other kind of windows) that gives you options like transfer pics , music, files etc......
You can copy your music onto your phone this way. Just remember what folder you put your songs in so that you can easily find them. I put mine in the Audio folder on my phone. Ill include the link to the program. But the first option is the easiest. The second one is easy to just alot of setup involved.
http://mytreo.net/downloads/card-reader,1122.html The card reader program isnt free but its a trial version for 30 days.