Actually, M-Audio's Key Rig is made for live performance and it sounds pretty good. By using Forte' as a VST host you can use Key Rig for both your live keyboard sounds and for your arranger style accompaniment or MIDI files (you would use the freeware MIDI Yoke as a virtual midi cable to connect Forte' to OMB or a sequencer). I think we all share the belief that Bandstand has the potential to sound even better than Key Rig, but Key Rig ain't too bad.

Here's a link to Joe Maas' tutorial on using OMB with VST's: http://www.1manband.nl/tutorials1/vst.htm