How to create the perfect background image

I have a background image that I want to use on a webpage. I will probably use CSS. The background image will contain a person in the background that will be to the left of other content (开发者_JAVA技巧like a voting box, fans listing, etc). How do I go about it so the bg picture shows perfectly regardless of the resolution of the computer, the size of the window, and browser used, etc.

There's an updated version of bgStretcher, bgStretcher II.

All you need is a bit of jQuery, here is the plugin to stretch the background proportionally..