1440x900, pretty damn small.
However, I would say it would be best to make your resolution to fit on any 16:10 resolution (preferably the highest you can get on your monitor), so that it will fit any other 16:10 resolution fairly well, as most people these days seem to use 16:10 monitors. You could also make 16:9 and 4:3 versions if you really wanted to, which would cover everyone (of course, those with smaller or larger resolutions than what you picked may have to change a thing or two here, but overall it will be fine).