I just looked at the specs on Creative's site, and the ONLY difference what so ever is the I/O bay and the remote. They are the exact same card otherwise... the XtremeMusic even has the pins to connect it to a drive.
On an unrelated note, coincidentally, I just traded a Platinum Card, a set of Logitech X-530 speakers, and a GeForce 7300 for an Xbox 360.