You may also consider a VGA switch if you are going to use the TV often to avoid the hassle of disconnecting and connecting cables on the back of the computer. Something like this which unfortunately is out of stock at the moment.
Your best solution would be to have a new video board that supports two monitors (many are HDMI these days) and you could run an HDMI cable between the computer and TV and use it as a second monitor. I have this setup where a 32-inch HDTV is the secondary monitor and extended desktop. To watch someting there I just drag to that screen and maximize or go full screen while keeping the primary monitor available for other things.