The purpose of this study is to see if patients with chronic kidney disease have endothelial cells that don't function properly, which is thought to be a marker for cardiovascular risk. Endothelial cells line the heart and blood vessels. The investigators will treat your high cholesterol with a cholesterol-lowering drug (atorvastatin, or Lipitor). They will determine if this cholesterol lowering drug improves subjects' cholesterol as well as the function of endothelial cells.