hello.I would like to display my computer screen on tv... What do i
need to buy in order to that? i need this in order to show my
powerpoint presentation on a TV for people to see... thank you

Hi,
If you are lucky, you may be able to get your hands on a tv which can
use VGA cables. VGA cords are what connects your pc to your pc montior
so all you have to do is take the cord out of the pc and connect it to
your tv.
Chances are your tv cannot do that so here are some other ways...
This can be done using a pc to tv converter, starting at about $40.
http://sewelldirect.com/pc-to-tv.asp?&
Otherwise it can be done by connecting the S-Video on your PC to the
S-Video on your television. S-Video inputs/outputs look like this:
http://tell.fll.purdue.edu/hatasa/kurosio/pages/svideo.jpg and are
sometimes yellow in colour.
You will need a cord to make the connection and to do this go to your
local electronics store and ask (that is if you do not already have
one).
Also some S-Video cords can plug into the AV ports on your television
which can be watched on the video channel as simple as that.
I am not a Google answers researchers but am trying to become one. 
If you can please give a dollar :)
For more information refer to:
http://sewelldirect.com/connecting-your-pc-to-your-tv.asp

I found a better way...
Put the Powerpoint onto a dvd, using this program:
http://www.freedownloadscenter.com/Multimedia_and_Graphics/Video_and_Animation_Tools/_1_PowerPoint_DVD_creator.html