of course that LED really just shows that power is getting to the pump. For a real pump failure LED I guess you'd want to wire up something like LMandrake did at overclockers with a Hall sensor:
http://overclockers.com/tips642/
He posts here sometimes so if you go this route he might have some pointers or advice.
I would personally prefer something like a "pump's working fine" LED and a pump failure shutdown circuit. Wouldn't make me feel better to have fried hardware due to pump failure and know it when I came home immediately because the LED on front of case was red and not green
