Just purchased a new Dell running Windows 7. Monitor is an Acer H243H connected with HDMI. The image does not fill the screen - there's about a 1/2" gap between the image and the edge of the screen. The display set up indicates 1920x1080 resolution.
Had the same problem with a new Windows 7 computer running integrated radeon 3000 graphics. After enabling GPU scaling, I had to go into the scaling options and change it to 0% underscan.