I dual boot my laptop with Windows XP Pro and Ubuntu, recently I had installed Windows 7 to test out and lost my Ubuntu system at boot up, but after searching the Ubuntu Forums I realised I’d lost my GRUB settings and still had Ubuntu safety on my laptop. Here is what is did.
Reinstall GRUB after Windows install:
Insert Ubuntu Live CD and restart system.
Open a terminal once in Ubuntu and do the following:-
sudo grub
find /boot/grub/stage1
Take not of whatever find states (hdx,x)
root (hdx,x)
setup (hdx)
quit
Now restart the system and remove the Live CD when instructed to. When the system restarts you’ll notice GRUB is back 
Short, sweet. This worked perfectly and was very simple compared to the confusing multiple options at:
https://help.ubuntu.com/community/RecoveringUbuntuAfterInstallingWindows
Very nice post. Very easy to follow. I will definitely be giving this a try when I return home this evening.
My system is back up and running thanks to this simple instruction. Much appreciated!