It's 2011... how wide should my websites be?

You should check out Responsive layout. Nowadays with both desktop and mobile devices consuming websites, there's a need to code for different environments and display resolutions. Read more there: <a href="http://maki.bo.lt/responsive-layout" rel="nofollow">http://maki.bo.lt/responsive-layout</a>

If you are designing for a fixed width, you're doing it wrong. Make your design scale to the browser window.

Same width as the user's browser window.