The pros probably already know this: but for us slow learners, I have 8.0 c and 8.1 on a dual boot system (xp pro x64 & vista ult x64. Make sure that the partions that the os are on are both primary or vegas will try to read the primary one and it will shut down when trying to start in the one that is logical. I know it's "basic 101", but it took me three days and two incident reports to figure out my vista partition was logical, I forgot to change it when I installed vista on that partition. Of course sony helpers didn't figure it out. All they could say was uninstall and reinstall. Everything is running smooth --so far and I am getting much better rendering times especially with the threads reduced to a number less than my eight cores. HMMMM !? Oh well onward and upward