GRUB can be edited using vi editor as follows
Boot from the ubuntu live cd/or boot from image using chroot.
We must edit grub.conf after logging in as root.
Code:
root @ localhost root $ vi/etc/grub.conf
Type the following in grub.conf below the entry for linux.
Code:
title Windows
rootnoverify(hd0,x)
chainloader +1
Here hd0 is hdd===>number may change sometimes. "x" should be 1 or 2 depending on hdd no. If its hd0 , x should be 0+1[or] if it is 1, x=2