One of the great features included with the TMG firewall is the ability to use mutiple ISPs.
This was a feature that a lot of people asked for, and they finally got it with TMG.
But did you know that you could bind low priority traffic to a specific connection? You bet!
Check it out at:
http://www.fastvue.co/blog/extending-forefront-tmgs-isp-redundancy-features
HTH,
Deb