I have Vista up and running on my Mac Pro. The hard drive is running in DMA mode! I already had XP running via Boot Camp and just did an upgrade. It took pretty long and there were a couple of hitches but it is working. I had one reboot where it just went back to XP like nothing ever happened so I restarted the install. It went pretty far then I had a blue screen. It continued installing and took forever on the "completing install" phase. First thing I did was check all the IDE channels and ALL show DMA mode. In device manager, there is no driver for "Base System Device" and I couldn't get one to install from my Mac drivers CD. There is also an "Unknown Device" right below it. All seems to work fine though. It also shows 4 CPU's where XP (Home) only showed 2.