You need to open the patch select window and choose your sound from there (it's the "P" on a midi track in the mix window). You also need to assign MSB and LSB (bank select) numbers for each sound from the patch select window. Your description suggests you've figured that out. There is no oms preferences and instrument lists in XP at all. Everything is done from the midi strip, that is selecting the channel, bank, and patch, but no devices. If you can only use one midi instrument at a time, that would suggest you're keyboard isn't multi-timbral (capable of making many different sounds at the same time). Check page 302 of the manual for more on bank selection. Hope this helps.