I think you are right. 1024x768 is common these days but from what I see from the stat, still some people use 800x600. But they will have to upgrade their monitors soon because the technology is changing faster. I am planning to go for a Samsung 19" Wide TFT monitor.
It depends on the choice of the client. But, these days as there are varied sizes of the monitors its better we follow a resolution that is compatible in all of them. So, these days most people go for 800 x 600 or 1024 x 768 resolutions. Both are standard resolutions and the rest depends on the clients choice. Example you can see PIXINT (800x600) & Steppy Frog (800x600) websites.