Screen Resolutions? What size fits most

Just a question for everyone. I am in the  process of redesigning the layout of our standard look and feel for most of our Lotus Notes applications. What resolution do you think can be accepted as the normal? We used to design for 800x600 but I think that going up to 1024x1280 is probably reasonable nowadays. However I would probably like to go to a higher resolution again but that might be pushing it. Anyway if you have any thoughts on what should be the average resolution I would appreciate it.