I tend to think of 1024x768 as the minimum Screen Resolution that a modern web browser will run in, but I worry when using this resolution for a business website because I feel that I might be hurting the folks out there who are stuck with something smaller/older. So I ask, realistically, what is the minimum screen resolution I should expect my website to function perfectly in with the browser "maximized"?
Look to the Netbooks for a new minimum. I'd say 1024x600 is reasonable.
Edit: You can always look to any number of sites that give you statistics on browser usage. Here's one that Google turned up for me: