A 42 inch plasma TV, I doubt it can get less fuzzy. You're trying to use a TV as a monitor and this doesn't always work out perfectly, they aren't made to be monitors. Plus its a very large screen size and doesn't support resolutions that should go with it, my guess is you are running at 1920x1080 which isn't (at least to my eyes) very pretty on a screen larger than 30inches.
I am not familiar with how the pixel are arranged on a plasma HDTV. However, on a LCD HDTV the spacing between pixels is greater than that of a PC monitor. This results in "fuzzy looking text". It's also a way to reduce the cost of manufacturing a LCD panel of an HDTV. If the spacing in between each pixel (pixel pitch) was less, then the size of each pixel would need to be larger to maintain the same LCD panel size.
I would expect the pixel pitch is rather large in a plasma HDTV as well, thus leading to "fuzzy looking text".
There is an overscan setting in the catalyst suite. Usually most radeon cards i've setup with HDTV's will account for some overscan. this can make the text a bit fuzzy. if your hooked up through HDMI then i suggest setting it to 0