[CentOS] Need Dual Boot Installation Help

During CentOS 4.1 Installation, I selected Advanced->GRUB Boot
Loader->Install to /dev/hda2.
(the /dev/hda1 partition as XP on it)

After reboot, I still only get XP booted and no choices for CentOS Linux.

I tried GRUB-INSTALL /dev/hda2 at the boot prompt, but that does not
execute.

What am I missing?

TIA,
David