right. First of all, you need to back up your data. install grub on a floppy:
http://www.gnu.org/software/grub/man...0boot%20floppy
install windows. get it all set up, then plug in the floppy and then reinstall grub on the MBR.
To look at your partition table, put in the knoppix cd and at the first prompt type
knoppix 2 <enter> and then use
cfdisk /dev/hda to have a look.
this should be a simple exercise- you also want a boot disk for debian incase things get messy.
blessings for your endeavour!
titanium_geek