Here it is a great XMas gift for you !!
After a long road and rounds of updates the Forefront TMG Team just released the new version of the famous Unsupported Configurations, this is great article to read PRIOR to deploy TMG. The reason why I’m emphasizing “prior” is because the worst thing that it can happen is to deploy TMG (or any software) and when a problem arise, you call support and you find out that the way that you did deploy (or configured) is not supported.
Read the full document here: http://technet.microsoft.com/en-us/library/ee796231.aspx
Happy Holidays !!