GRUB is a third party boot loader that I used for a while as a means of triple booting between Linux and two Windows installs.
When it came time to restore the system to single boot I was faced with the question of how to remove GRUB without damaging any of the Windows installation.
The process was surprisingly straight-forward, despite some worrying posts I read on the Intertron.
This thread contains some useful info, but this is all I had to do:
1. Alter your BIOS to boot first from CD
2. Boot from the XP CD
3. When prompted select Repair
4. At the C:\WINDOWS prompt enter the following commands:
5. Reboot and change BIOS back to boot from HDD
6. If necessary edit the boot.ini file to remove any lingering OS entries that you no longer need.
Job done :)