1. Try using Supuer Grub Disk to reinstall Grub, and in the process it may detect Windows.
2. Add the entry mainually. This is my entry:
Code: Select all
# This entry automatically added by the Debian installer for a non-linux OS
# on /dev/sda1
title Windows XP & Windows 7
rootnoverify (hd0,0)
savedefault
chainloader +1