I'm gonna suggest one of the ScanGauge products. They're a code-reader that can also reset stored codes, as well as can monitor/display almost anything that the engine computer is putting out on the diagnostic line. I see you have a Windsor and you'd use the ScanGauge D version. I have the gas engine versions in both cars, too.
Ok, Johnboy2 just beat me to my other suggestion... the VMSpc. Awesome product.