I have used a .cab to change the 'sprint music' tab to a 'music' tab. It was in one of the cleanup threads. With this mod I essentially have wmp open all the time but without the excessive memory usage. I can play a song and scroll through to other tabs and I can pause a song, visit another tab, and return to the song right where I left it.
I'm not sure if you're using it in the same way I am but here's the link to the mod I'm using:
http://forum.ppcgeeks.com/showthread.php?t=44583