If you want to put music on it, your going to need to download SonicStage
This program is used just for PSP and other Sony software
It will convert your audio files to an Atrac format, which basically compresses the music to a smaller size without lowering the bitrate
You'll be able to add in ALOT of music files if they are in atrac format
I own a PSP, and i primarily use it for Music. I have a few games, but i rarely ever play them.