Red Squirrel makes a good point and www.basepump.com also carries a piggyback system with two electric sump pumps, one above the other, so when the water levels are normal, the lower pump takes care of it, but when the water comes up higher, the second pump kicks in. You can also install a separate alarm for when both fail as well as a backup sump pump using either water or battery power for when the power goes out or the pumps fail for whatever reason.
I might be wrong,but wouldnt an audible alarm drive you crazy?
I was suggesting an audible alarm for when the pump wasn't working. I see no benefit of having a light come on when the pump comes on. Who cares when it's working? You should only be concerned when it's not working - hence the alarm.