I installed Windows 7 after I had installed Ubuntu 10.4. Windows 7 overwrote the Linux bootloader “grub” on my master boot record. Therefore I had to restore it.
I used the Ubuntu 10.4 LiveCD to start up a live version of Ubuntu. While under the LiveCD, I then restored the Grub bootloader by chrooting into my old install, using the linux command line. This is a fairly complex thing to do, and so I recommend you use this approach only if you’re are confident with the linux command line:
# (as root under Ubuntu's LiveCD)
# prepare chroot directory
mkdir /chroot
d=/chroot
# mount my linux partition
mount /dev/sda1 $d # my linux partition was installed on my first SATA hard disk, on the first parition (hence sdA1).
# mount system directories inside the new chroot directory
mount -o bind /dev $d/dev
mount -o bind /sys $d/sys
mount -o bind /dev/shm $d/dev/shm
mount -o bind /proc $d/proc
# accomplish the chroot
chroot $d
# proceed to update the grub config file to include the option to boot into my new windows 7 install
update-grub
# install grub with the new configuration options from the config file, to the master boot record on my first hard disk
grub-install /dev/sda
# close down the liveCD instance of linux, and boot from the newly restored grub bootloader
reboot