My older brother recently inherited an older sony laptop P3

Its in good running order and operates using the ME addition operating system. He uses it primarily to watch videos that I give him via our home network, but he has a huge projection TV on his side of the house that we are room mates in together and I was wondering if it was possible to buy a graphics card for his laptop that had component or s-video plug-ins so that I could connect it to a TV and have him watch avi files from the hard drive onto his television. I plan on doing this secretly for him as a gift and most likely will have a technician install it for me unless it turns out not to be as complicated as I hear.

Now is this plausible or is the sony model and maybe operating system to old and cannot support a radieon or any other graphics card with those add-on features??

You may be able to buy an external unit that would work, but it would be expensive. There will be nothing that will work with a Sony laptop PIII for internal use.