My guess is that the Empeg's DHCP client isn't doing this?

Actually, it is. I just checked my DHCP logs from the past few days, and the two new units on the LAN are passing their name off to the server, spaces replaced with dashes.

So Tonys setup is working because of the Windows voodoo magic in WINS or another protocal, and his network does not suppot DDNS (Dynamic DNS) tied into the DHCP server needed to do this on a pure TCP/IP level.