WMA-DRM on PSP??? Help!

Hi!

I have a huge collection of legal music on my computer. However it is in the WMA-DRM format.

There is no limitations on the DRM (this what they say), except a 30-day membership that must be renewed once a month.

I wonder if anyone knows how to transfer the license files from my computer to the PSP in order to be able to play my music on the PSP.

Whenever I just copy the .wma files on the PSP, it says that the data isn't compatible and cannot be played.

However, SpiralFrog (the online music store which I downloaded my songs from) says that I should be able to play the .wma files on a portable device if I sync the license files once a month with it...

PLEASE HELP ME!

How do I transfer WMA-DRM files to the PSP ? (And please, don't talk about illegal workaround)

(and sorry for my bad english :D)