I've searched this topic and I can't find an article with a plausable solution, to my problem.

I installed windows 7 first, with 100gb of disk space. I created the necessary partitions via windows. Then I installed Ubuntu 12.04 on the remaining 400gb of disk space.

During the Ubuntu installation I installed the ubuntu boot loader on /dev/sda3 which Windows (as expected never granted me the option pre-boot for which OS I wanted to boot). So I re-installed Ubuntu on that /dev/sda3 partition, overriding the windows 7 loader.

Now when I boot windows 7, it runs GNU Grub, so like an infinite loop.

How can I reconfigure grub to say:

/dev/sda is the bootloader. /dev/sda2 is Windows. /dev/sda3 is Ubuntu.

Re-installing windows and my partitions isn't an option, purchasing software for windows isn't an option (theres a reason I use linux, it's not because it's free, because you don't have to install lots of shit to get stuff working, and over-all it's a robust OS).