Sorry to start another thread, just rejoind the list after seeing the 
online journal of the posts.  I a haveing the same isse.  Short of 
setting up a 1:1 NAT and just allowing all TCP/UDP to the Xbox, I have 
tried to configure 1.23b2 and 1.3b2 with NAT allowing TCP/UDP 88 and 
TCP/UDP 3074 forwarded to the Xbox360... still showing "moderate" in the 
Xbox Live connection.

I am going to enable more logging and see if I can't figure out what 
other ports it is trying to tickle.  If someone gets this before me 
shout... thanks!

-F