Source: .net Magazine (couldn’t find the link)
Here are the latest stats on who has what for screen resolutions:
1024x768 - 57.38%
800x600 - 18.23%
1280x1024 - 14.18%
1152x864 - 4.95%
1600x1200 - 1.67%
1280x800 - 1.56%
1600x1024 - .55%
Other - 1.48%
Hope this data could be of use! 