If I understand your question correctly, what you need to do is convert
your MP3s to WMA files, and then either transfer them to a MicroSD
card, or use Verizons Music Essentials Kit (USB cable and drivers) to
transfer your music using Windows Media Player 10. MP 10 will convert
your files to WMA automatically. They're sticklers for DRM, but I
haven't run into trouble yet with any of my MP3 files.

I ended up returning my a990 and getting a SonyEricsson w810i with
Cingular service. Now that's one cool phone, and it isn't at all
crippled like the a990 from Verizon. This is not bashing Verizon, but
they are particularly restrictive. I mean a 3mp camera and you can't
transfer the pics from your camera with a USB cable? What's wrong with
this picture (pun intended)?