These reports show the screen resolutions and the color depths used by your visitors. This is essential information for the design of your web site. Make sure that you create your pages using the same equipment as the majority of your visitors.
For example, if most of your visitors use Microsoft Explorer with Windows Vista, a 16 million colors screen and a resolution of 1024 x 768, then you need to look at your site under these conditions. Most likely you will be surprised by the result... Don't forget that you are designing your site for your visitors, not for yourself !
Note that screen resolutions and color depths can only be captured if you use the standard or advanced version of the 123Stat code on your site. The simplified code will not record that information.