I have a 19" 5:4 LCD monitor hooked up to my desktop computer. Manufacturer recommends 1280x1024, but at that resolution some Windows components are too small to read comfortably, even using large fonts. I use 1024x768 instead.
I also have a hp netbook running XP hooked up to a 42" plasma TV. The only resolution that's comfortable to see at a normal viewing distance of 7 feet is 800x600.