  A strategy to determine the luminosity at Hadron Colliders is discussed using
the simultaneous W-boson and Z-boson event counts. The emphasis of the study
will be on the uncertainty induced by the parton density functions.
Understanding this source of uncertainties is crucial for a reliable luminosity
determination using the W-boson and Z-boson events. As an example we will use
the D0 run 1 results to extract the luminosity using the vector boson events
and compare the result with the traditional method. Subsequently we will look
at the implications for the top cross section uncertainties using the extracted
luminosity.
