Oliver Sommer 
2009-09-17
Microsoft just published the Feature Pack 1 (FP1) for Windows Essential Business Server 2008 (KB973236) which allows you to setup the way the TMG firewall seperates your internal network from the internet. For example the FP1 allows you to completly turn of the firewall function if you have another frontend firewall and just use the poxy functionality of TMG instead.
FP1 is downloadable here:
http://www.microsoft.com/downloads/details.aspx?displaylang=en&FamilyID=40274ca7-9f0d-4152-b090-3980442e7222#tm