Please help with metrics and config

I posted, in a different newsgroup, in regards to this before, and got
all of the way to what I need to do to resolve my issue, but not how
to actually do it. If anybody can help, I would be very greatful!

What I want to do:

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 2601 connected to the
frame. 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 was, 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

The answer I received is as follows:

What you can do would be to setup a backup default route w/ a lower
metric that point out the frame (you would do this on both routers on
the frame) so that should the internet connection go down, there would
be a route that allows you to go out through the Frame {ie- ip route
0.0.0.0 0.0.0.0 Serial0/0 (Frame) 200 (metric) }

To have your network traffic go across the internet, you would
essentially need to do the same thing as above (with a backup route),
but would need to setup an IPSEC tunnel between the two routers "in
the event of..."

My new questions is:

It was said that we should set up a backup default route with a lower
metric that points out the frame. Is there a command for backup
default ip routes? Would the 200 metric used in the previous example
be the correct metric to use? I don't know if there is even a metric
setup for the default route. I'm sorry for my lack of knowledge and
experience. This is the first time I have actually implemented any
configuration like this and just want it to work correctly.

Thank you for your help. It is very appreciated!