Boot off knoppix disc. Open up hdb1 and find boot/grub/menu.lst file. Open it up a text editor: sudo kate /mnt/hdb1/boot/grub/menu.lst

It should have different sections, 2 for Knoppix & 1 for Windows.
My Debian box's menu.lst file looks like:
Code:
title           Debian GNU/Linux, kernel 2.6.8-2-686-smp
root            (hd0,7)
kernel          /boot/vmlinuz-2.6.8-2-686-smp root=/dev/hda8 ro nomce noacpi acpi=off
initrd          /boot/initrd.img-2.6.8-2-686-smp
savedefault
boot

title           Debian GNU/Linux, kernel 2.6.8-2-686-smp (recovery mode)
root            (hd0,7)
kernel          /boot/vmlinuz-2.6.8-2-686-smp root=/dev/hda8 ro single
initrd          /boot/initrd.img-2.6.8-2-686-smp
savedefault
boot

title           Microsoft Windows 2000 Professional
root            (hd0,0)
savedefault
makeactive
chainloader     +1
Your Windows section should match mine. The "title Microsoft Windows 2000 Professiona" line should not matter.

Your Debian/Knoppix sections shoudl look similar to mine.
The changes made to my lines to make it work on your system should look like:
root (hd1,0)
kernel /boot/vmlinuz-2.6.8-2-686-smp root=/dev/hdb1 ro nomce noacpi acpi=off
If these changes are made then it should work. Save the changes & exit the Kate editor.

You may also have to reload grub to the Master Boot Record. Make sure /dev/hdb1 is mounted. Then:
Code:
sudo chroot /mnt/hdb1 /bin/bash

grub-install /dev/hda

exit

sudo umount /mnt/hdb1
Then reboot.

If you have difficulties please post the entire menu.lst file.