Menu to let me choose OS to run in a dual boot machine

view story

http://askubuntu.com – I recently re-imaged my Dell PC to dual-install Windows 7 and Ubuntu 12.04.1 LTS. The dual-boot was a success, since I was able to start whichever OS I wanted. Now, I installed some software (the OpenJDK package) on the Ubuntu side of the PC. Upon restarting Ubuntu, I unfortunately lost the ability to choose the OS that I wanted to run (i.e., Ubuntu). Ordinarily, I'd expect to: 1. Hit the power button 2. A menu (Grub?) shows up listing all OSs installed in the PC (namely, Win7 and Ubuntu) 3. Choose which OS I want and hit enter. bingo. The problem is that I don't see that menu (step 2 a (HowTos)