I have a 22" Samsung Syncmaster T220HD display connected to a Dell Optiplex GX280 SFF PC via HDMI. Recently, I purchased a Sapphire ATI Radeon HD4550 DDR3 512MB PCI-Express low profile video card. When I set the resolution to 1920 x 1080i or 1280 x 720p the picture is in HD; however, when set to 1920 x 1080p the picture doesn't show in HD. Why is this? Shouldn't 1080p be in HD??