I was fat and happy with a dual boot Mini 9 until I upgraded Snow Leopard to 10.6.2. The upgrade went well but I had to run NetbookInstaller .8.3 RC4 to get the kernel patched. Snow Leopard would boot OK but Windows would no longer boot. I booted into the Windows 7 Install (USB) and ran "Repair my computer" and the darn thing wrote the MBR to the USB device and not the Windows partition. So if I tried to boot the Windows Installer on the USB, Windows on the internal disk would start up. Of course I could no longer get to the Installer to Repair my computer any more. Once more I re-formatted the USB drive, made it bootable, and copied the Windows 7 Install package. When I ran Repair my computer the second time it wrote the MBR to the internal disk and now I can dual boot again. I must be the only guy that can screw up the Windows partition this way.