You can re-install without losing anything, apart from 20 mins. Or you can do some thing a little technical using the Knoppix cd as it was intended to rescue your existing install. Or you could install a boot loader that I use, OSL2000. OSL2000 will find lilo on the root partition (as well as the windows bootloader) and you can use this method.

As for using your knoppix cd: -

1. Open root shell and type the following
2. mount -o rw /dev/hdb1 /mnt/hdb1 (where hdb1 is the partition you installed to in linux terminology. To check start up "qtparted" and find your ext3 drive on the picture and match it to its name/label [type "qtparted" in the terminal])
3. chroot /mnt/hdb1 (chroot = change root. You are now the root user of the filesystem on partition hdb1)
4. vi /etc/lilo.conf (this opens up the unusual vi text editor)
5. boot=hda (find the line in lilo.conf that says boot=hdb1. To boot directly from lilo every time you start your computer you must install to the MBR. So boot=hda install lilo to MBR of first hard drive, boot=hdb installs to second. To actually edit the line move your cursor to the boot= line and press i. Make changes and then press ESC. Type ":wq!" without quotations to save and write file to disk before exiting.
6. lilo (make sure it is successful. If not post back the exact results)
7. Control + D (exits session)