Just discovered new build of Parallels which ostensibly includes support for Vista SP1. Didn't receive an announcement - just happened to notice it on versiontracker.com. I'll report later on how it all works (or doesn't) work out.
Good News and Bad News The good news seems to be that a Boot Camp Vista SP1 installation seems to work, although the performance is nothing to jump up and down about. It's performance rating is 1.0 vs. 4.0 on Boot Camp running natively. The bad news is that in Linux, the Parallels Tools still won't install correctly into the latest build of Ubuntu