Failover Route

Please Advise!

I am trying to find the best way to failover my internet connections.
I have two networks that both have an internet connection (completely
different ISPs for redundancy). At each location we have a Cisco 2801
router connected to the internet, and a Cisco 2600 connected to the
frame relay. We currently do not use the internet connection at our
second location (want to get it up and running as soon as we can), and
the only way that location gets to the internet is over our T1 frame.

My question is, how can I setup the Cisco 2801 as the primary route
for our internet connection (as already setup at our first
location),but failover to the Cisco 2600 on the frame if the internet
goes down at either location? We currently use static routes, and
wonder if setting up dynamic routing is the ONLY option. Also, if I
have to use
dynamic routes, is there a way to setup which path is the primary
path, and which is the backup or failover?

Here is a basic layout of our network:


Cisco 2600---Network A
| \
| Cisco 2801
| \
Frame| Internet
| /
| Cisco 2801
| /
Cisco 2600---Network B

Also, we would like all network traffic to go over the frame
primarily (as it currently does), and failover to Cisco 2801 over
internet if the frame goes down. We want to setup WWW access through
Cisco 2801, all other traffic through Cisco 2600 unless one or the
other is down.

Thank you for your responses!