Mark up your Monitors!
Here is a good tip for designers:
Open each of the console windows. Then mark and label the edges of the console on your monitor frame.
When you design, you can drag the browser edges to fit the marks during preview to see what the screen will look like to the users with 640x480 and 800x600 monitor resolution. Notice the 779x434 console size--this is the typical size of the screen ("realestate" or "canvas") that your users will see.