Use TV As Monitor, If You Can
In the last few years I started to think more and more about protecting the environment especially because I see most people around me completely ignoring this. For example I upgraded my video card not because I really needed more video juice but because the new one draws less power and now I am really glad that I'll build a computer for someone who won't need a monitor... and this naturally takes us to the subject today: if you're not using a monitor what are you going to use? Obviously you'll end up using your TV as monitor!
Unfortunately not every TV can be used as monitor for your computer but even if you'll have to get a new TV it's better than purchasing a TV and a monitor don't you think? Since I won't tell you "Get that model from LG!" or "You have to get a Sony LCD TV/monitor they are great!" because it wouldn't be fair at all I will try to guide you in making the right choice for your needs and budget.
Ready or not here you have the big things to think about before deciding to use TV as monitor...
1. Who is usually using the TV and who needs the monitor? Let's suppose that you're living in a room with your girlfriend and she wants to watch some soap opera exactly when you want to play some online game with your friends - in this case you shouldn't use TV as monitor... unless you don't know how to make her leave you! ;)
2. Check the back of your TV (or the one you want to buy of course) to see the available connections; if you're buying one ask about it. To connect a PC a DVI or VGA input should be enough. Speaking for myself I think HDMI is useless for most people but having the capability to directly play files from a USB drive is something you should also look for since it becomes more and more popular and is decently priced.
3. See if your computer has DVI output - as long as your TV also has it this is the best way to connect them but using the VGA cable ain't that bad either. If you have a VGA input and only DVI output on your video card don't worry - adapters are not expensive at all and they're not hard to find either.
4. Be sure to check the native resolution of the display especially when buying a new TV/monitor - a lower end LCD TV with 1024X768 resolution isn't such a smart choice to be used as TV and monitor...
5. Try to get only the additional features you really need - for example a TV/LCD with good speakers could help you drop those computer speakers you had and gain some space.
I guess these are some major things to think about when trying to use a TV as monitor and if you're thinking about using that old TV your mother had for over a decade... it may be done but using the S-video/composite connectors may not deliver good results at all especially if you look around at these LCD TV/monitor wonders available for pretty low prices!