As well as H.264 is one of the most nowdays advanced video codecs and the future for HDTV, I think all of us should encode (almost read) this video codec.
So if your system don't have natively implemented this codec you can go to x264. It is a free version encoder for H.264 and gives a good enough results.
Also for those who want to decode this implementation of H.264 they can install ffdshowfor windows systems or ffmpegor VLC media player for windows pr mac systems.
A very good review of how to encode x264 in windows is here. For reading h.264 encoded movies for mac or windows, here. For linux is fully implemented with ffmpeg and mplayer ... if you are a linux user probably you already knew it
Hope it help you in your projects.
Best
Genete