Sreen size and resolution have to do with your video card and monitor. You monitor will only support up to what it was designed for which means if you have an old monitor with a newer video card chances are you will only run at about 1024 X 768 on a 17inch. The bigger the monitor the better the resolution and the better the video card has to be.
1600x1200, the highest my current video card supports. Newer video cards can do 2048x1536. (*wipes drool from mouth*)
It is worthwhile to note that if you have a laptop or an LCD monitor, there is only one resolution you should use -- the native resolution of the fixed-pixel display device. Unlike a conventional CRT monitor, an LCD cannot vary the sync rate to work at any resolution. An LCD is always running at its native (highest) resolution. So if you have a laptop or LCD monitor that is capable of 1280x1024 and you have your resolution set to to 800x600, 1024x768, or anything but 1280x1024, you are doing yourself a great disservice and sacrificing loads of video quality by "scaling" your video through non-linear stretching and interpolation algorithms. I can't believe the number of laptops/LCD monitors I see using the non-native resolution, making the display look awful. (TechTV article here in case I didn't explain it well.)
A high-resolution fixed-pixel display (i.e., a laptop or LCD monitor) combined with Windows XP's ClearType technology provides stunningly sharp text that is a joy to read (sample at bottom of link). (To turn on ClearType, go to Control Panel > Display > Appearance > Effects and turn on the checkbox for "smooth edges of screen fonts," making sure that the popup menu reads "ClearType." Only enable ClearType on LCD displays -- it is not designed for use on regular monitors!)
Remember, the original laser printer was 300 dots per inch. A typical display is 75 dots per inch. By increasing your resolution to 1600x1200 or 2048x1536, you are getting more and more dots per inch. Someday we'll be able to buy high-res displays that can do 300 dots per inch. Increased clarity increases reading speeds. For example, enabling ClearType has been shown to increase reading speed 10% to 15%.
