Question : Ensuring a Reliable Internet Connection

I need to setup a really good internet connection framework.  That is, I have software running that must absolutely be connected to the internet while running.  I can't constantly monitor the connection so I need to come up with a framework that does.  This is a home computer that is using   cable.  As far as I can tell, the cable internet connection is fairly reliable.  But, I can't take any chances.

One suggestion made to me is that I setup a router with both DSL and Cable so if one connection goes down, the router can switch to the other connection.

Does anyone have any simpler ideas?  Is there software out there that ensures a reliable connection, monitors it, and takes appropiate action if the connection goes down?  If not, can someone tell how to setup the router solution in the basic way possible?

Also, if there's a better zone that the ones I've chosen, please let me know.

Answer : Ensuring a Reliable Internet Connection

BTW define uptime...   7x24 with 99.999% uptime? (~max 4 hours down per year)... or is 99.99% uptime sufficient.

If you need that uptime you need to eliminate ALL single points of failure, not one router but multiple, multiple switches, multiple servers, multiple connections (possibly through multiple technologies DSL, ISDN, ATM, dark fibre), multiple locations? Look at power suplpy (independant sources) cables (network, power etc) not entering a building all at the same spot, but ALSO not merging a few miles down the road. Have multiple ISP's, have X hours of autonomy when power fails if you need autonomy for about 10 minutes, organize a generator set, with sufficient fuel, (and rotate the fuel with fresh fuel every year ) etc.etc.

So please define uptime, Allowed downtime, the time the is allowed RTO (return to operation), allowed MTBF.. based on that requirements you can estimate how much insurance in double equipment, double maintenace you can accept.