a big enough jump from 42" to make a difference. You will need to sit closer to the screen on the 50" though, because the text will not get blurrier but it will get smaller obviously.
If you plan on using it for movie and TV watching also, you should definitely get the biggest TV you can afford. The size would make much more of a difference with movies and TV, then it would with being used as a PC monitor.
If you do care about movie and TV watching, I would recommend that you go with the Samsung PN 50A550 plasma. It was highly rated. I have seen it in person and will vouch for it myself. It will be great for movies and TV and unlike most TVs, it will display a VGA connection at 1920x1080. Most TVs, regardless of whether it is a plasma, LCD, or RPTV, limit VGA resolution to 1366x768 (sometimes even lower).
Check out that Samsung. It could be a good match with your needs.
I am going to use my TV as a computer monitor, and I'm going to get a set that has 1920x1080 native resolution and PC inputs.
My question is: Does the text clarity and sharpness decrease as I move up in size of TV given the same viewing distance, the type of computer input (DVI to HDMI cable), and the source signal resolution?
I would think that it would because you have a fixed amount of pixels (1920x1080) that are being stretched onto a larger area as the screen size increases. Thus, a 42 inch screen will show a sharper computer screen picture (text, etc.) than a 50 inch screen if both viewed from the same distance.
My reason for asking is that I thought that I wanted to get the biggest screen I can afford, but I'm starting to realize that the sharpness may decrease to such a degree on a larger screen that I may opt for a smaller one for clarity purposes.