Huzzah Astro! Over the past couple days I've looking at the idea of changing my system to a dual-boot: XP -> XP/FreeBSD. The dual-boot superguide link you provided suggested same path forward as I had assumed, but it's good to see it spelled out nonetheless.
I have Partition Magic so I'll be using that to carve out my FreeBSD niche. I'm a little concerned how much of an obstacle the GRUB/NTLDR issue will be. I've read that you can be faced with "NTLDR Missing" message if NTLDR isn't found in the MBR. I guess I'll just have to cross that bridge when I get there. I have an old laptop so I will probably try using that as a test platform before jeopardizing my XP desktop.
I'll let you know how it goes.