Once you get it working, look into "ultramon" it is a must with multiple monitors imo. You can have different resolutions wallpapers and screensavers with ultramon. You cant with default windows settings. utramon gives each monitor its own taskbar as well which is real handy.
I switched from ultramon to Actual Multiple Monitors
and highly recommend it. It is a most powerful utility among others and it works fine under Windows 7. The most important feature for me is an additional taskbar on my second monitor that has all features of main taskbar like Start button and tray area with notification icons. Even more, it has Pin to Taskbar feature of Windows 7.