One of the most requested features for ISA Server 2006 has been the ability to combine two DSL lines, mainly in order to be able to leverage both ADSL lines (load balancing) and have redundancy (failover backup) as well.
This scenario is possible with Forefront Threat Management Gateway (TMG), the new version of ISA Server currently in Beta 3. Using the capability called ISP redundancy which basically, enables utilizing two ISP links for external connectivity, either for traffic load balancing or as a failover backup.
You can download Forefront TMG Beta 3 in both Standard Edition and Enterprise Edition from Microsoft Download Center.
More information about basic setup steps, configuration, monitoring and some caveats and tips and tricks is available at the Forefront TMG (ISA Server) Product Team Blog.
Source: Technet Blogs
