posted earlier about a problem dual booting with windows 7 (with little info to help you help me, I had no sleep for exams) and figured out my problem finally... if you upgraded to 7 from vista your problem may be that debian didnt autodetect your 7 OS behind the vista loader left behind when you upgrade. if you upgraded to 7 like I did, try adding a new entry like this to the grub in /boot/grub/menu.lst:
right after vista loader. goodluck
title Windows 7 (loader)
oh and remember to go remove the vista loader partition later id didnt even realize it was there....