Trouble setting up multiple boot on big disk

[Brett Glass]

I'm setting up a laptop which will need to dual-boot Windows 2000 Server (ugh!)
and FreeBSD. I partitioned the large (60 GB) hard disk so that there was
an 18 GB NTFS partition at the beginning, followed by a 20 GB partition for
data, followed by an 18 GB partition for FreeBSD. But when I attempted to
install FreeBSD, the disk labeling utility wouldn't let me divide the
18 GB partition (or "slice," in traditional UNIX parlance) into file systems
("partitions" in UNIX parlance). I get an error message that says I can't do
it because something's "too big."

What limitation am I hitting, and how do I get around it?

--Brett Glass