As far as your question goes, I'm assuming u technically mean from your SD card to PC, as it's not practical to store music on your handheld
buy an SD card reader.
Walk into a retailer like Staples. They sell SD/MMC card readers for $20 (low as $12 if u shop online or wait for a sale). $40 (low as $20 if u shop online or wait for a sale) for multiformats that also take Mem Stick Pro/Duo, CF, SM, XD, microdrive, etc. Latter is useful if u work with other flash media formats, but being larger, more difficult to carry w/u to work or on the road
This is a more portable SD card reader if you're on the road alot. Unlike the reader above, this one's got no long wires or relatively big reader unit.
Be sure to get a reader that's USB 2.0. The PC receiving the music must have at least USB 1.1. USB 2.0 is preferred to transfer lots of music quicker. Plug in the reader, the card into the reader, and u got yourself large floppy or pen drive right there. Drag and drop music files over. Palm Desktop not required.
There's a software only app called SoftStick or CardExport which turns your flash card into a big USB drive mode. I think this requires Palm Desktop to be installed on the receiving PC tho. No hardware card reader required tho/