Configure a Persistent Static Route on Windows Server 2003
From Peter Pap's Technowiki
Surprisingly, this is much like creating a static route on a Unix box.
1. Bring up a command window
2. Use the route command to view the current routing table
route print
3. Add your route using route -p target_network mask netmask gateway_ip metric costmetric. Eg.
route -p add 192.168.80.0 mask 255.255.255.0 192.168.50.1 metric 1
The -p makes it persistent, so if you just want to test, you can omit this and the route will disappear after a reboot. The metric is an integer cost metric (ranging from 1 through 9,999) to be used in calculating the fastest, most reliable, and/or least expensive routes. If costmetric is not specified, 1 is used.
For more detail, click here