Network Load Balancing is something you get right out of the box with Windows Server. But what if you want to use that platform capability with your TMG firewalls? Well, you can, but you’ll need to create an array to get it to work. For details on how it works and how to configure NLB with TMG firewalls, check out this article by Ricahrd Hicks here on ISAserver.org
HTH,
Deb