Dual Monitors

I have wanted to set up dual monitors for a little while now. I find it really cool to switch from one monitor to another, while using the same mouse and keyboard. It also really helps with productivity and organization. The only thing is I'm not too sure of how the setup works. I have done some searches through the web, but that hasn't really helped me enough. I have the second monitor in my room, but the Dell Dimension 2350 desktop I have now doesn't have the graphics card to support dual monitors, so I need to upgrade my graphics card. I figured someone here at Geeks may be able to give me some insight on some steps I can take. I would also like to know any suggestions on a graphics card I can purchase and whether it should be a graphics card from Dell or a different brand that will work with my desktop. So, if you have any helpful tips to get me started on setting up dual monitors, please let me know. Thanks.