Yes, you can. What kind of television? Most HD TVs have a PC input the same as computer monitors. For a standard definition TV, most laptops have a video output and the laptop usually comes with an adaptor cable that converts the video adaptor into RCA plugs so that you can use the usual video cabling (I use it to hook my laptop up to my TV to view videos that I recorded). Be aware that you will get really horrible resolution on a standard definition TV - it's OK for video watching but I would not want to do anything else with it.
HD TV : You mean to say the conversion of video is taken care by TV. and no compromise with video quality.
SD TV : Conversion takes place on computer (laptop or desktop). and output would not be good. Yes I have also faced this issue while giving presentation using Projector. Resolution/Color Scheme gets changed.
laptop usually comes with an adaptor cable that converts the video adaptor into RCA plugs so that you can use the usual video cabling
I guess I have SD TV and Desktop PC. So I guess I need video adaptor card. But as the output is not as good as HD TV id it worth spending money?
Regarding HDTV, there are two commonly-used resolutions: 720p is 1280x720, and 1080p is 1920x1080. Hook your PC to one of those and that will be your desktop's resolution. Of course, if you have a 50" screen, you will probably need a wireless keyboard/mouse because you will have to sit quite a ways away from it (desktop use is out of the question!).
Regarding SD TV: the projector you used probably had either 800x600 or 1024x768 resolution (I usually run into the later). A SD TV has 640x480 resolution (actually, I think it is really 320x240 with some interpolation that gets you 640x480, at least that what I recall from ages ago when I was using an Atari 800 and learning how to do sprite programming and read a series of articles that described how TVs worked and thus how to do smooth animation - it involved knowing the number of clock cycles for each 6502 processor opcode and how many clock cycles there were in a vertical and horizontal reset). Personally, I would pay for an LCD monitor, even decent ones have come down to reasonable prices.