If you look at your grub.conf file, you'll see a line like:
If your grub.conf file has multiple operating systems listed, GRUB numbers them as they appear, starting from 0. On my system, I have two Linux images I can load, and my Win2k partition. Win2k appears last, and that means GRUB considers it #2. So to set Win2k as my default, I'd change the default line above to:
Piece of cake. As for lilo, I'd have to read up on it bit. I think all you need is a proper LILO configuration file, and then to run:
DO NOT take my word on that though. Read the man page to double-check me.