By coincidence, I have been working on the same conumdrum today in getting the Sony M2TS files being played in Vista Windows Media Player 11.
Previously, like other members, one was getting sound but no picture. I too have looked in the past at codecs from Cyberlink with no success.
In the last few moments, I have download the free full codec pack from K-Lite see:
http://www.free-codecs.com/download/...Codec_Pack.htm
Installed it, ensuring all other windows were closed down ensuring that M2TS files were associated with Windows Media Player and that my current version of ffshow was uninstalled (The program will give you the option to do this).
Clicked on a M2TS file and hey presto, one now has this file playing in Windows Media Player! (Please note, the picture has quite a few jaggies when displayed in half-screen size but these are virtually eliminated when one views in full screen. I am running this on a 2GB HPM3075. Not sure whether increased memory and processor power would help).
Now my last wish is to be able to play the same M2TS file in slow motion. Media Player (as with MPEG2 files) doe not allow you to play in slow motion. This only seems to work if I make the file a DVD (VOB) but then of course I'm losing quality of picture in converting to the Sony High Quality MPEG2 (8Mbps). Anyone got any ideas on how to get the slow motion working?