I use visualHub / iSquint but it takes ages, I wish there was some app similar to what Windows have, a application which basically changes the file container instead of the encoding... still searching tho
As it stands, for me, the best is Visualhub. It's faster converting x264 to .avi imo, since the 360 now supports .avi via Connect360, doing that is better than .mov or even .mp4. I do however from time to time, convert x264 to .wmv, not noticed much differences yet.