Question : Two Groups, Two ISPs, One domain

Two groups of users - a school ( faculty and students ) and an administrative office group - share a single physical network and Win2k3 AD domain.  Each group has its own organization unit.  All network computers run WinXP Pro SP3.

The two groups previously had separate physical networks each with its own ISP.

We want to have the school users access the Internet via one ISP and the admin office staff access the INternet using a different ISP.  If one ISP goes down temporarily we would like to be able to have both groups use the available remaining ISP until the other is back online.

Can we use two NAT routers for this by configuring TCP/IP for computers in each group to access the appropriate gateway?  

For the reliability feature can we configure all computers to use the other group's gateway ( and appropriate metric ) as a secondary gateway for access if the group's primary connection is down?

Thanks for your help with this.

Answer : Two Groups, Two ISPs, One domain

You can only have one default gateway on a computer.

I would say the answer to this is dependent on what kind of devices connect you to the internet.  A Fortinet Fortigate Unified Threat Management Device (UTM) supports multiple ISPs and should be able to load balance and even direct traffic based on subnet.  I would probably be creating 3 subnets - one for the servers, one for the faculty, and one for the students.  Then on the student subnet, assign them to the ISP gateway you want to use for that, and then the server and faculty would be assigned the other gateway.