* Boot with the first Installation CD and type 'linux rescue' in the boot prompt. The installer anaconda will mount RedHat installation under /mnt/sysimage.
* Type 'chroot /mnt/sysimage' in the rescue shell that you get.
* Open '/boot/grub/menu.ls t' in your favourite editor and add the following lines to the end it it.
title Microsoft Windows
Note: Its assumed we installed Windows to hda1. If you have doubt do 'fdisk -l /dev/hda' to find the your C:
hda1 -> (hd0,0)
hda2 -> (hd0,1)
and so on.
* Then type 'grub-install /dev/hda'. It will report that installation of GRUB completed.
* Reboot using 'reboot' command and you will be getting GRUB with two entries one for Linux and other for Windows.