To reinstall XP without losing the music (admittedly, you'll lose all the settings and the music database - which isn't a problem if you tagged the files properly) simply get the recovery console up (Windows Setup from the CD, press 'R', enter admin pass) and:
code:
cd C:\
attrib -s -h -r ntldr
del ntldr
del WINDOWS /F /S
del "Program Files" /F /S
This should allow you to reinstall Windows while keeping the documents and settings folder (I'm assuming this is where the music is, if it's not, simply mkdir C:\Music and move all the music into there).