Windows it displays "chainloader (hd1,0)+1"
This is the problem in /boot/grub/menu.lst. As root, edit the windows entry in menu.lst to look like this:
title Windows (or whatever you want)
map (hd1.0) (hd0,0)
map (hd0,0) (hd1,0)
Windows will refuse to boot if it isn't on the first partition of the first hard drive (hd0,0). The map lines tells windows a little white lie to make it think it's on (hd0,0).