A very useful link which provides TMG 2010 tools, here we go http://www.microsoft.com/downloads/details.aspx?FamilyID=8809cfda-2ee1-4e67-b993-6f9a20e08607&DisplayLang=en
This is on ISA /TMG product blog( http://blogs.technet.com/b/isablog/archive/2010/05/24/error-502-proxy-error-the-request-is-not-supported-50-while-trying-to-access-websites-from-web-proxy-clients-behind-isa-server-2006.aspx )
A quick one, whenever you are configuring you cache drive and dont know how to define the cache drive size. Please use following formula
10MB + 0.5*Number of users=size of of cache drive
let us say Number of users is 500 then cache drive should...
For migration from ISA server 2006 to TMG 2010 one very usefull document is http://technet.microsoft.com/en-us/library/dd440994.aspx
Still we have to make sure we are doing couple of things right e.g. when we install TMG 2010 following the wizards...