I spent a couple of hours getting a proprietary software H.264 codec working in Linux and even published a writeup to help others. A day later I learned from one of the people I sourced in my article that nVidia started releasing Linux drivers last November for the hardware high definition decoders found on the 8xxx series of video cards as well as a customized version of mplayer to support the new drivers.
A mixture of emotions came across as I realized I wasted an entire day on a software decoder when a hardware solution was available for $30 to $40. The software solution was fairly disappointing, so I decided to try one of these new cards, an nVidia GeForce 8500 GT, to see if it provided a better solution. It took some work with my setup, but the results were worth it.