Top Background to SM Higgs Searches in the $W^{+}W^{-} \to l\nul\overline{\nu}$ Decay Mode at CMS

The top quark and its properties within and beyond the Standard Model will be extensively studied at the incoming Large Hadron Collider. Nonetheless the top quark will play the role of the main background for most of the Higgs and new physics searches. In this paper the top as a background to H=>WW=>2l2nu Higgs discovery channel will be studied. The current status of the Monte Carlo tools for t-tbar and single top simulation will be presented. Finally the problem on how to evaluate the top background from the data will be addressed and the related systematics will be discussed.