belltt,
If you are paying for 2 different connections then as Jimbo said above - you want a dual WAN router.
Most can load balance your traffic and the very least that they can do is take over when the other connection is down.
As Jimbo said - if you Google "dual wan router" you will get a ton of info and reviews!
Hope this helps!
E.A. Broda
CCNA, CCDA, CCAI, Network +