Windows server 2008

How can I set up 2 internet conection on win server 2008?
The conection vill be like 1 LAN port and 2 WAN ports with 2 differnts internet operator which never vill be at same time working, its only one at time.
I want that windows vill handle the “failover” not a router if possible.
I had before a similar with win 2003 and 1 adsl conections. I just bridged 2 network adapters but its not possible when you have 2 gateways.

Thanks