I bought a PC to Video cable (http://grandtec.com/ultimateEZ.htm) that just converts your monitor signal to a RCA style video cable. This works great and does not require S-video cards in your PC, nor S-video on your older/cheaper TV's.
You will also need a cheap audio converter to convert from your PC head phone jack to the RCA style jack on your TV or Stereo. There are also fancier audio converters, but the audio signal over the web is very low quality, so you are not losing anything.
All of the above can be done, but if you are going to watch a lot of games I would just buy the satelite system or find a local bar that will tune the games in. For me watching the games on your TV is better than a PC, and watching at a bar is better yet.