1) Download ubuntu alternate install iso.
http://releases.ubuntu.com/precise/
2) Install
3) Reboot...But no Grub2 is installed.
4) Install Grub2.
http://www.howtogeek.com/114884/how-to-repair-grub2-when-ubuntu-wont-boot/
sudo add-apt-repository ppa:yannubuntu/boot-repair
sudo apt-get update
sudo apt-get install -y boot-repair
boot-repair
5) Reboot. Should have ubuntu entries.
6) open terminal. sudo update-grub. Win7 entry will be added to Grub2.
