I have an ASA 5505.
Primary ISP is a T1.
Secondary ISP is a Cable connection.
I remember reading that a PIX was able to do a failover type setup with this setup. Setting up a timer that would ping a destination, and if that IP stopped responding it would inject the Secondary ISP's route.
Is this possible with this ASA 5505?
Yes -- as far as I know, this should be possible with the ASA 5505. The feature you are looking for is called Static Route Tracking.
See these two pages:
One difference you should see on the 5505 from the other 5500 models is that you are using VLAN interfaces instead of physical interfaces. You just assign the physical switch ports to be members of the seperate VLAN's.