My system has 1280×1024 screen resolution. In my system my design is looking good. But in other systems like 1024×768 screen resolution the design is looking bad.
You can either choose to use liquid/fluid layouts, or you set a base resolution for the "lowest common denominator" when it comes to your clients viewing your site. Right now it's still 1024x768.
I personally don't think anyone is still "really" using 800x600, and if they are, I don't support them