personally for my xp machine I let xp set itself as the default OS then use a floppy for lilo
ie change line 1 of /etc/lilo.conf to "boot=/dev/fd0"
then (as root) type "lilo" , with the boot floppy you are going to use in the machine. its the simplest way, my girlfriend understands it, floppy for linux, nothing for xp.
btw to remove lilo use the command "fdisk /mbr" from dos.