W2K Server uses AFP 2.2 for Mac File Services and this is limited to 31
characters.
To get longer names you'll need to use the SMB protocol to connect from Macs
running Mac OS X 10.1 or later or you'll need to use a third party
application such as Extreme Z-IP, which supports the AFP 3 protocol.
Windows 2003 Server also uses AFP 2.2 as well, I believe, but I'm
researching this to make sure.