No you do not need to buy one of the HDMI Receivers, HDMI and DVI (HDCP) switcher boxes are available today at a reasonable price, the price will drop even more, and quality improve as demand increases next year.
The Malpin one would work, but you do not need it yet.
There is no need to worry about a single DVI or HDMI entrance on your panel today.
Wait for PS3 to come out in 20??, then get a switch box, enjoy your LCD today.
The new AV amps have new features such as 7.1 dolby, and upscaling. They are a one box solution.
Your LCD will upscale internally anyway, these products just do it better (apparantley) by using deciated circuits and improved components. At least that the advertising burb, ultimately you have your own set of eyes.