Essential Audio and Video Codecs
If you are running Vista x32 or x64 and want to play the usual set of audio and video files (such as mp4) you might need additional codecs. The one which has worked with me on Vista x64 is called the K-Lite Mega Code Pack v1.61; however as I said in my previous post, it might have caused an issue in DVD playback though I am not 100% sure of that.