Influencing OSPF Routes

I have a 2 Cisco routers and a Cisco VPN concentrator in parallel, plus there is another cisco router sitting behind them.

-- VPN Concentrator--------------- Internet| |---------Cisco Router3 -- Cisco Router1---------------------- -- Cisco Router2--------------------

OSPF is running between the all 4 devices. There is a route towards the internet out of each router, and there is a *Backup* Route for each cisco router pointing towards the VPN concentrator. For example, I need a way in ospf to have Router3 Prefer the Route thru Router 2, and if the wan link is down, have Router3 prefer the route over the VPN conentrator. In addition I need Router3 to prefer the route thru Router1 and if its wan link is down, have Router3 prefer the route over VPN.

Keep in mind that there are multiple "primary" routes to each of the cisco routers, so costing the physical links will not work. I need a way to cost each route on Router3.

Thanks