Also, check to make sure you have the lastest driver updates for your graphics card and your chipset, check your manufacturers website. If there's no Windows 7 drivers for your model, use Windows Vista ones.
Under power options -- what do you see? You should see "plans" and "change plan settings." If you select "change plan settings" for the plan you are on, you will see additional information as far as standby, display dim, hard drive shut off, etc.