If you want it to work as a computer monitor
then you have to get a computer monitor....this is how it used to be. Historically, computer monitors will work as TV's but not the other way around...although this definition is becoming blurred with there becoming so many LCD TV's. It used to be that TV did not have the same same sharpness as computer monitors. Was you need to make sure is that it is first intended to be a computer monitor. Fortunately, in your size range, monitors are very inexpensive. Make sure the monitor you buy has the right ports
for connecting to a TV or for connecting to a TV tuner in your PC or for connecting to an external TV tuner. Switching between your computer and your TV tuner will be a simple matter of selecting which port you choose to use on your monitor. Most monitors have a button right of the front for doing this.
The more resolution you have and the better smaller your dot pitch
the more detail and the clearer will be your picture. Also look for brightness and contrast as secondary factors to consider. In general, the larger the monitor you get the more pixels that can be squeezed onto a screen
which means the more resolution you can get which will make you happier if you get a high definition player. In that case try to find a monitor with a HDMI IN port. Some monitors now even have built in tuners..which makes them a TV? See how the definition is getting blurred?
This 20" Samsung HD capable monitor does have a TV tuner. I'm kind of partial to Samsungs TV's and now their monitors.