i've had issues with multibooting freebsd 5 and linux. i recommend installing freebsd before linux because linux seems to do weird things that confuse freebsd. theoretically it's possible to install linux first then freebsd, but ive had issues with it in the past.
for a bootloader, i highly recommend
GAG. it lets you boot up to 9 different OSes and is really easy to install. you should make a GAG bootdisk as a backup and see if the freebsd or LILO bootloader works well, and if not, either modify them or just install GAG.
so you're trying to install linux, bsd and win on one hdd with xp on another? keep in mind the 4 primary partition limit when you're doing this.