Dual Monitors- Once you go dual, you'll never go back!
I've used dual monitors since the days of Windows 98. Really I could probably make the switch to a single monitor, but only on one of the newer, large, and wide screen units. This page is not going to look very pretty for a while as I'm putting it together fast and dirty. If you click on the screen shots below they'll link to the full version of the picture - warning - you'll probably have to scroll across to see the whole picture! You'll notice that I have the task bar on the right half of pictures and that is where you can tell the monitor on the right begins. I normally use the "Auto hide" feature of the taskbar, but have it shown for the purpose of the screen shots. I'll also try to link to some other pages that tell about setting them up.
You can see that I have pidgin, a multi-protocol chat/messaging program, open on one monitor and a web page open on the other displaying the live radio/web show "The Tech Guy". That way I can watch the show on one monitor and still interact with the chat room that supports the show on the other and not miss anything. Some programs are especially good when using mulitple monitors such as the web page editor Dreamweaver, which can use multiple windows to display all the files in a site on one window and the page you're editing on another.
Do the Google search and you'll find many pages with links about Dual Monitors. Just make sure if you do go to those pages, not to get sucked into too many programs and add-ons. If you've got the hardware, video card(s) and the monitors, the video card will have everything you need to get started and Windows will have the support built in. This means you don't need to spend a bunch of money on extra software.