I followed the guide from here:

http://osx86.sojugarden.com/category/working-with-os-x/

This was because both my Mac OSX and Win7 partition are on the MBR-partition scheme.

The only difference from the directions was I set Mac OSX active using Win7 diskpart, and not in MacOS terminal. Win7 gets confused if you do it through Mac OSX. You have to repeat it several times (first set Win7 active), then boot into Win7 using the disc, and then set your Mac OS partition active.