  We study the sources of systematic errors in the measurement of the W to
lepton and neutrino cross-sections at the LHC. We consider the systematic
errors in both the total cross-section and acceptance for anticipated
experimental cuts. We include the best available analysis of QCD effects at
NNLO in assessing the effect of higher order corrections and PDF and scale
uncertainties on the theoretical acceptance. In addition, we evaluate the error
due to missing NLO electroweak corrections and propose which MC generators and
computational schemes should be implemented to best simulate the events.
