Mission control is somewhat nice, but it doesn't hold a candle to the very simple and time-tested method of using alt-tab. Alt-tab is ridiculously fast, works on windows instead of applications, and doesn't require you to switch to the mouse and visually search for the proper window.
Also, a new feature of Windows 7 (actually I think it first appeared in Vista) is Win-Tab. It is like alt-tab, but gives you a preview of the windows instead of their icons. If you really need to see what a window looks like while switching through your windows, that's the way to go. I don't care for it, as it's a bit laggy, but then so is Mission Control on my Macbook.