Go to the virtual machine folder.

sudo usermod -a -G disk jpv

install-mbr -e12 --force windows.mbr

VBoxManage internalcommands createrawvmdk -relative -filename windows.vmdk -rawdisk /dev/sda



In Virtualbox attach the new disk to the SATA storage setting.

Start the virtual machine.

Your normal boot menu will show, make sure you select Windows, it might not be a good idea to start the host OS as a guest in itself.

Windows will spend some time detecting new drivers, etc. and then boot up.

If Windows reboot too many times, try using the install DVD's repair function.

Note: If you don't want the normal boot menu to show, look at the MBR option of VBoxManage (-partitions 1,2 -mbr windows.mbr) I could not get it to work.