OK, I'm 13 old so sorry id if you dont understand this or I dont answer you inmedeatly because im @ school
OK first what is not perturb Win XP?
OK then if you got internet from your knoppix install this works in Debian and should in knoppix if im right and im remembering it good:


1st ok open a command line and: apt-get install grub grub-doc
2nd grub-install /dev/hda Using in place of /dev/hda the device that you boot from
3rd: update-grub This creates the menu.lst (the table of partitions)
4th then lets edit the boot list: editor /boot/grub/menu.lst go and read the grub manual and how to add OSes here:http://www.gnu.org/software/grub/manual/grub.html and if you cant then answer me.
5th: apt-get remove lilo to say goodbye to LILO dpkg --purge lilo to say goodbaye to its configuration files

Good luck