Fdisk /MBR in Windows XP
Windows XP doesn’t provide Fdisk, but I’ve done an equivalent operation to FDISK /MBR like this:
Configured the Recovery console for automatic administrator login - this was important because there seems to be a bug which requires an admin password to be entered, even when the system doesn’t have one.
http://support.microsoft.com/kb/312149/Then boot up from the Windows XP setup CD, and I chose the ‘R’ Recovery option.
Once in, I ran FIXMBR.