If your TV supports HDMI, then use that. You will get a better picture on the TV. A quick way to get it going is if you have an HDMI set-top box/blue ray player then you already have the cable needed to hook it up and go.
Windows 7 Should recognize the new display almost instantly. If not you can right click on the desktop and go to Screen Resolution. At that point you should see two monitors, one will be grayed out. Click on the grayed out one and select extend my desktop to the monitor. (I believe) hit apply and as long as the tv is on, it should flicker to life with an image of your extended desktop.
Now if your TV is an older TV and doesn't support HDMI you will need a DVI (Male) to VGA (Female) adapter with an VGA Male-Male cable. You can get this at your local radio shack or electronics store that is half way decent. BestBuy & Staples along with most major retailers like them normally do not inventory them.
RadioShack charges about 12-20 bucks depending on quality and whats in stock.