Below you will find the Forefront Threat Management Gateway 2010 version numbers and their corresponding updates.
To find the version of TMG you are using, in your MMC, go to Help, and then "About Forefront Threat Management Gateway"
RTM, Service Pack, Rollup
Version
Reference
TMG 2010 RTM
7.0.7734.100
Service Pack 1
7.0.8108.200
http://www.microsoft.com/download/en/details.aspx?displaylang=en&id=16734
Update 1 for Service
Pack 1
7.0.9027.400
http://www.microsoft.com/download/en/details.aspx?id=11445
SP1, Update 1
Rollup 1
7.0.9027.410
http://support.microsoft.com/kb/2433623
Rollup 2
7.0.9027.425
http://support.microsoft.com/kb/2475183
Rollup 3
7.0.9027.441
http://support.microsoft.com/kb/2498770
Rollup 4
7.0.9027.450
http://support.microsoft.com/kb/2517957
Service Pack 2
7.0.9193.500
http://www.microsoft.com/en-us/download/details.aspx?id=27603
Rollup 1 for TMG 2010
SP2
7.0.9193.515
http://support.microsoft.com/kb/2649961
Rollup 2 for TMG 2010
7.0.9193.540
http://support.microsoft.com/kb/2689195
Rollup 3 for TMG 2010 SP2 7.0.9193.575 http://support.microsoft.com/kb/2735208