I hate those damn low fuel lights. Mine never seems to come on with any kind of consistency. One time it'll come on when the gauge is just above empty, the next time it comes on just below 1/2 tank. I use the trip meter and just reset it each time I get gas, figuring 120 miles until a refill.

By the way are you still hearing the fuel pump whine? If so you've got a hole in the fuel line that's inside the tank. The whine you hear is the fuel pump trying to pressurize the fuel line.