Grub, removed Linux Partition and RestoreIT

I used to have 2 partitions on my machine: winXP and Linux Mandrake (now Mandriva). I installed Linux after Windows, and it added its own boot manager, namely, grub. So far so good.
This was one year ago, and I hadn't used Linux for several months since then, so I decided to remove the Linux partition, with PartitionMagic 8. No problem.
A few days ago, I installed RestoreIT and used all that fresh freespace for backup purposes. RestoreIT tampers somehow with the MBR, as it gives the option at boot time to enter an admin console and revert to some backup. Then grub loads as normal.
My problem is, I don't need grub anymore, as I've only one bootable partition. However, I now don't know how things are organized. I suspect RestoreIT claimed ownership of the MBR and moved the previous MBR somewhere else; is that correct? If yes, I'm doomed and can't get rid of grub, unless I uninstall RestoreIT, right?
Let's say I uninstall RestoreIT (which I'm not willing to do right now), how should I proceed to remove grub, now that I don't have Linux?

-RE