The solution to this problem is pretty much everywhere.
At the end of the file, add:
Change (hd0,0) to the partition Windows is on. A number prefixed with hd refers to the hard drive number, the second parameter is the partition number. The count starts with 0. So first hard drive is hd0, second hard drive is hd1, et cetera. Likewise, first partition is 0, second partition is 1, et cetera.
So if you want first hard drive, first partition it's (hd0,0)
first hard drive, second partition (hd0,1)
second hard drive, first partition (hd1,0)