Please be informed that 1280x1024 and 1600x1200 are 4:3 aspect ratios at full resolution. This means that you can use 1600x1200 for desktop resolutions 800x600 and 1024x768. You just have to choose "stretch to fit screen" on macs and "fit to screen" on windows. 2560x1600 is widescreen version perfect for widescreen monitors such as apple cinema display and others.
