Resolution and Screen Size.
When you buy a monitor it can come in a variety of screen sizes; 15"-19" are the most common sizes. This measurement is taken diagonally across the screen, including the plastic part of the monitor around the edge. The viewable size is the actual size of the glass part of the screen, which is also measured diagonally across the screen but not including the plastic edge.
Resolution is how many pixels the monitor can display at a given time. The smallest resolution Windows supports is 640x480 pixels (meaning 640 dots horizontally by 480 vertically). Better video cards and monitors are capable of much higher resolutions. The standard resolution used today is 1024x768. You might also hear resolution referred as VGA, SVGA, XGA or something similar. This is especially true with laptops or LCD monitors. VGA simply is 640x480 pixels, SVGA=800x600, XGA=1024x768.
Resolution can be adjusted under the settings tab in the display properties menu located in the control panel. In addition the number of colors the computer displays can also be adjusted there. New computers should run at 32 or 24-bit color. Older computers that perform sluggishly should be turned down to 16-bit or 256 colors. If you are experiencing problems with your video card turn the resolution down to 600x480 and 16-bit color.