If you're using a newer web browser (Netscape 4.XX or IE 4.XX or newer), your screen size should be automatically set to a correct value.

If you're using another browsers, Yahoo!7 Games allows you to select either a 800x600 or a 640x480 screen size, depending on the size of your monitor. The default size is 800x600. The games are the same, regardless of the size you choose.