Assuming you can authenticate from 10.3 using Active Directory, in Active Directory open the user's account. Select the "Profile" tab. Under the home folder section, choose "Connect." Select a drive letter -- be careful as this will map a drive to that letter on the PC side of things. Enter the path to the home folder as \\server\share - make sure the share is actually shared out.
That's it. If you have more than one Active Directory server, it may take a while to replicate throughout. If you need to mount more than one share, it requires schema modifications or a client-side login script. I hope to submit a hint with my solution in the near future.
Mac OS X Hints
http://hints.macworld.com/article.php?story=20031107115119887