This may be a very nieve question
I have a router with two outside interfaces to the internet, a cable modem and a dsl modem. The internal network is a very simply small business network with a server and 5 workstations.
Right now i am working with static routing, and when the faster interface goes down, I bring up the slower interface.
Should I be running one of the dynamic routing protocals and if so which one.
The environment that you describe is so simple that I do not see any real benefit in running a dynamic routing protocol. With 1 small LAN and and 2 external interfaces, the only one that comes close to making sense would be BGP. And your situation does not really justify BGP.
So work with static routing. If you want to get sophisticated look into reliable static routing with object tracking.