There is a way to enable routing on an NT server, I'm trying to think back to what it is. You have to have two NICs and I believe on each NIC you have to go to the properties of TCP/IP and go to options. From there you want "Enable IP Forwarding". If it's not in the properties of TCP/IP, keep looking within the network applet. The option you want is "Enable IP Forwarding".
Hope that helps.