I install different operating systems in addition to my primary os, WinXP. In order to do this, I use the GAG bootloader. GAG can be installed either in its own http://gag.sourceforge.net/
or from the SystemRescueCD: http://www.systemrescuecd.org/changes-x86.en.html
My advice is to NOT to use the bootloader that FreeBSD offers. Instead, you should use GAG. This has worked very well for me, and I suppose that it will work well for you also.