My Mac Pro was a stock dual 2.66GHz model with 1GB RAM. I upgraded it to 3GB with OWC's chips. I also added three 500GB hard drives to the other three bays with two of them set up as a RAID 0 and the third set up as a Windows Vista Build 5536 (pre-RC1) under Boot Camp 1.1. When I start my WinXP VM, it'll give me the VT-X error as seen by many here. If I sleep my Mac Pro and then wake it up and start Parallels and the VM, it will kernel panic reliably. So I'm running my VM SLOWLY with VT-X off. At least it works.