800x600 here, no need for anything higher, well unless you want to get real close to you monitor.
I would maybe go one step higher with a 19"
What is the advantage to having a higher res? besides a little less scrolling in some aps.
The original question was about building a web page, i think you should stay at 800x600 or 1024x768 as thats what the majority of web surfers are using, acording to visitor stats anyway.