Found answer for your question at :
http://hometheater.about.com/od/hometheaterbasicsfaq/f/htbasicfaq5.htm
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A. Let me start off by saying that any modern
television can be used in a home theater system. In essence, if you
already own a good, working, television that has at least standard
audio and video connections in addition to a standard cable or antenna
connection, you have at least a basic way of viewing television and DVD
images. The question is whether you need to upgrade to a more advanced
television, or, in home theater lingo, a video display device.
Don't Get Bogged Down With The Techie Stuff
Here is where consumers get bogged down with the terminology and
potential choices. Where once there was only the good, old-fashioned
25-inch tube TV, now consumers have the choice of not only a dozen
sizes from 27-inches to 73-inches, but also have to choose between
tube, plasma, LCD, rear projection, and front projection.
The size of the television or video display device you get really
depends on the size of the room environment you will be using it in and
how close you will be sitting to the screen.
However, the decision as to what type of television you get is a little
more complex. However, no matter what type of television or video
display device you purchase, make sure it is high definition
compatible, even if you don't access to high definition programming
yet; this will change very soon.
With specific reference as to whether one should get a television-type
video display vs a video projector, the main factor you have to take
into consideration is whether you intend to watch a lot of television
programs vs DVD movies.
Factors To Take Into Consideration
Important factors to take note of when considering a video projector vs a television-type video display include:
1. Video projectors do not have RF cable or antenna connections
like a television has. However, if your cable or satellite box has
either S-Video, component, and/or DVI (for HD components) connections
you would be able to hook them up to a video projector.
2. Video projectors have a very limited bulb life. In other
words, if you are watching TV on your video projector about 3-4 hours
every night, you would have to replace the light source bulb about once
a year at 200-400
dollars a pop.
3. Due to the very large screen sizes used in video projection,
standard TV or satellite do not look as good as they do on standard
large screen television. In addition, VHS looks very poor, due to its
low resolution.. If you have HDTV-cable or HDTV-satellite , you would
get much better results.
Ideally, video projection really best for viewing DVD movies and, if you
desire longer bulb life, limit your viewing to about 10 hours a week and
your projection bulb will last about two years.
If you are looking for a replacement for nightly TV watching,
it would be more cost effective to buy a large screen rear projection
television, LCD, or Plasma set rather than a video projector."
