If you can boot from the install CD, you should be able to enter
rescue mode (normally by typing rescue at the prompt, instead of pressing enter). Once you've done this, you can edit your lilo.conf file and change the first line from
boot=/dev/hda1 to
boot=/dev/hda and then rerun lilo to install it into the MBR. You might also like to ensure that you have an entry for Windows in your lilo.conf file... else you might find it difficult to boot Windows