[LAU] controlling xruns in a VM

I'm working on a Parallels VM running on my MacBookPro to give a Linux audio demonstration to ouI'm working on a Parallels VM running on my MacBookPro to give a Linux audio demonstration to our local LUG and seem to be getting the best performance from Fedora 10 extended with CCRMA. Tried ArtistX, Ubuntu Studio, JAD, and Musix too, and just upgraded to Parallels 4.0 with significant improvement in functionality and performance, but that was after setting up Fedora 10 and deleting the others so I don't know if any of them would leapfrog and wind up in a better position than they occupied under Parallels 3.0. Anyway, if any MacBook or other OS X user has found an optimal configuration for running Linux audio in a Parallels VM (and I know that's not how you'd do critical audio work), I'd appreciate any tips you might pass my way. Currently, I'm using built-in input and output set in OS X's preferences and for the VM, and in jack 1024 frames/period with 4 periods/buffer in RT. Folks at this WNYLUG (wnylug.org) here in Western New York are quite interested in virtualization technology as well as audio work so I'd like to be able to give them a good look at both. Thanks for any suggestions or help. Frank