gpart bootcode

I seem to have messed up the mbr on a particular disk which has Windows installed and can't boot the disk. I can view the partitions using ntfs-3g and they seem intact, so I wondered if I could restore the MBR using gpart bootcode -b /tmp/Windowsmbr ada0 if I managed to find a copy of Windowsmbr...
You can boot off a Windows CD, drop to a Repair console, and run fdisk /something to restore the default Windows MBR.