With the functionality of the xbox at the moment, there really isn't much of a need to convert to wmv as there once was. I fought that idea for a long time, but it will end up causing you more frustration than anything, not to mention super long conversion processes. Either convert to mp4 or use the process I described earlier to play mkv files, or pay for a program to do the conversion for you. It gets a little trickier when trying to maintain 5.1 sound because you usually have to demux the video file first so you get both a video and an audio file and then recombine them back into a wmv. For this process I used tsMuxer to demux the file into both a ts video file and a separate audio file, and then I would use tmpgenc to re-encode those two files back together. TMPGenc is not a free software though.