It can be done, but there's no good reason to. To create separate pages for different monitor
resolutions is crazy, since there are dozens of different monitor resolution settings, and because
many people don't maximize the browser window anyway.
You can use Google Analytics (free, easy to install, and fascinating) to see what your visitors'
monitors are set at, and that (and some common sense) will give you a general sense as to what
size their browser windows are. Then, the task is to build pages which look good at the most
common sizes, and look at least decent at the less common sizes. I personally do that with
fixed-width pages. Other people swear by flexible-width pages.