connecting HD Antenna and Analog Cable to HD TV

You could try just feeding both the cable signal and the antenna signal into the outputs of a cheap 2-1 splitter, then connect the input to the HDTV coax input. However I think you'll get a lot of interference if there's two signals with the same or overlapping frequency.

My Sharp Aquos 45" LCDTV had separate coax inputs for analog and digital cable and antenna, so you could select any input source using the remote, then tune to available stations. My KDL52W3000 is similar to yours with just one coax input. Also seems to have worse picture in comparison to the Aquos. In particular I was noticing that Lost season 3 looks crummy on the Sony during scenes in which the camera is moving through the jungle - lots of pixel artifacts and fine details such as tree leaves, at 1080p, 1080i and 720p (have an upscaling DVD player connected via HDMI). Haven't tried 480i or p yet. However Lost looks fantastic on the Aquos, either in action scenes or just talking faces.

Unfortunately the Aquos developed a bad panel in less than 2 years and Sharp no longer makes that size or stocks replacement parts... I still have a week left to return the Sony so I might just do that and get the Pioneer 50" plasma instead.