Fran, Soundfonts are getting a little long in the tooth but they are not bad. You can start off with downloading (free) a wavetable such as the one recommended by AJ, namely SGM180. You can then acquire Soundfaction's Alive or use Creative Labs free Vienna to edit this table (change effects, change voices, replace voices, etc.). Finally you need a sample player to run the Soundfont Wavetable, e.g., LiveSynth Pro, SynthFont (
http://www.synthfont.com/ ), etc.
Even for the lower quality requirements for live performances, I would still recommend using higher quality lead or melody instruments. You could use the more moderate quality found in libraries such the Garritan Personal Orchestra, Garritan Jazz & Big Band, EastWest Colossus, etc. This in addition to any modules you may wish to use, e.g., B4, Guitar Rig, etc.
You can set this up similar to AJ's above example, i.e., separate instance of say kontakt with a separate instrument loaded on separate channels. The Auto Accompaniment would be run on a separate instance of the appropriate sample player say SynthFont within your host software.
I would like to ask AJ if he has tried the Plugsound GM Module and if he has what he thinks of it.
[This message has been edited by Frank L. Rosenthal (edited 11-03-2005).]