Have you checked with the MP3 manufacturer's website as to whether there are
drivers that needed to be installed before the device was connected to the
PC?
I have a PoGo AudioRave 128meg MP3 Player/USB Drive. It can be used as a MP3
player and a storage drive. It plugs right into the USB port. It should show
up with a drive letter when you plug it in. I have tried it on another
computer and it worked fine. No software to download,. WinXp should read it
as a drive.
Right click on My Computer and select Manage. On the following screen,
select Disk Management. Can you assign it a drive letter from the right
hand side of the screen?