Stat Counter on my 3 blogs a few weeks ago.
They confirm my sense, from other uses, that 1024x768 is the most popular screen res in use. This is just one of many useful background statistics available when I installed Stat Counter, and then visit the web site and check the status of visitors to the blogs. Only a very small number of users are coming in at a lower resolution.
This is the free version. I do not get any kick backs from suggesting them as a statistics generator.
Still working on the new image galleries.