the live cd that I have for ubuntu 7.04 does not have any such feature.
but you can use it to boot the machine...
Then mount the linux partition if this is not done automatically.
Check if the contents in /boot/grub/menu.lst are still correct (if you just reinstalled windows they will be and you can as well skip this step).
grub-install --no-floppy /dev/hdx (hdx being the drive you boot from)
and you are good.
This will reinstall grub as it where - windows always overwrites the bootloader with its own when you install it and I know of no way to prevent it from doing that - so reinstalling grub after a windows install is "standard procedure".
I think that works - but it might not...I did not test.
But this will: (change "yourharddisk")
mount /dev/yourharddisk /mnt/ubuntu
mount -t proc none /mnt/ubuntu
mount -o bind /dev /mnt/ubuntu
chroot /mnt/ubuntu /bin/bash --login
grep -v rootfs /proc/mounts > /etc/mtab
grub-install --no-floppy /dev/yourharddisk