My apologies for missing that. This is how I resolved my issue with that in the past.
Download the following and install it
Windows Server 2003 Resource Kit Tools http://go.microsoft.com/fwlink/?LinkId=4544
after installation is complete, click on: Start, All Programs, Windows Resource Kit Tools, Command Shell
Then enter the following commands. (Attention: they are case sensitive.)
net user guest /active:yes
ntrights +r SeNetworkLogonRight -u Guest
ntrights -r SeDenyNetworkLogonRight -u Guest
The first command enables network access for Guest, the two subsequent ones change two different policies to allow network access for Guest.
Kudos to fseal, and thanks to sup3rsprt for catching that for me.