How to migrate Microsoft ISA Server 2006 to Microsoft Forefront TMG
ISA Server 2006: Migrating to Forefront Threat Management Gateway.
Introduction
Microsoft Forefront TMG (Threat Management Gateway) is the upcoming successor of ISA Server 2006 and will be available in 2009. This article is based on a beta version of Microsoft Forefront TMG. If you want to evaluate Forefront TMG, a public beta is available at the following website: Forefront TMG. If you want to have a look at a special version of Microsoft Forefront TMG which is already RTM, you should evaluate Microsoft Windows Essential Business Server 2008 which contains Forefront Threat Management Gateway, Medium Business Edition. But keep in mind that this is not the same version of TMG which Microsoft will publish in 2009 as a standalone product.
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Source: How to migrate Microsoft ISA Server 2006 to Microsoft Forefront TMG