Windows 7 Dual Booting Vista Ultimate and Windows 7 Pro

Okay, i have two hard drives in my computer and one has Vista on it and now the other has Win7. Everything in Win7 is working great but i cannot boot up Vista off the other drive anymore, there is no option. I have tried to go into advanced system properties and see if i change the default OS but the drop down menu only shows Win7. Anyone got any solutions?

Boot to the Window 7 DVD/USB and choose repair. After it searches for Windows installations, it should find the problem straight away and add Vista to your boot menu for you.

Thanks, worked like a charm