Set up redundant networks using RRAS

[Pilot1]

We are currently using DSL to carry our data via IPSEC over the internet to all of our branch offices. We are finding out that DSL's are not Enterprise Class network services and experience a lot of undependable service, and slow response times. As a temporary solution to our troubles, I have been trying to establish RRAS routing via dial up modems for connectivity between branches. Has anyone had any experience setting up the correct routing I should use. I cannot get traffic to flow both ways. I suspect that a Routing Protocol like OSPF must be used to get routes to flow to our different subnets. For example I simply need to get traffic from site A 192.168.0.x to site B 192.168.1.x and vice versa. Site B would establish a demand dial connection to Site A when the network goes down. I have my gateways set to 192.168.0.4 at site A and 192.168.1.4 at site B when our VPN is up PIX 501's. The problem is that the gateways will change when using dial up Site A is 192.168.0.8 and Site B is 192.168.1.2 ( Windows 2000 servers). Can I use OSPF at each site, and setup DHCP to assign two gateways in the order of PIX VPN gateways first and Windows 2000 second? Windows DHCP servers exist at both sites A & B. I am confused on how to specify route's in this situation, and I have noticed that a reboot or an IPCONFIG Release/Renew is required for workstations to pick up the new gateway's. HELP. Let me know if there is any other info required.