I assume that pretty much any image will resize decently since it wouldn't be lowrez to start with, but I'd also say that from everyone's house I visit, the lowest COMMON denominator size wise is still 1024x768. Yes, lotsa folks with new systems have big screens or 16:9 aspect ratio screens, etc... but I suspect that numerically, 1024x768 remains the most widely used, as it will work on everything from old laptops on up.