I swear by Window Sizer:
http://www.voidnish.com/articles/Sho...de=windowsizer
Tiny, simple and yet indispensable for me, writing intranet pages for a business still riddled with 800x600 res monitors, while I enjoy a whopping 1280x1024. All it does is to re-size the active window on your screen to the dimensions you specify. But it saves me a lot of hassle switching my own screen res.