windows media video .wmv is good for nothing.
containers, ex.- = .avi , .ogm , .mkv , .mp4
vid codecs, ex. - = .Xvid/Divx , .mpg , .(something, i dont remember them)
typically videos encoded with Xvid are the best.. thy can come in any container format as shown above. assuming the encoder was compident as his job. the quality of Xvid can be in any of those container formats, but knowadays i think pro rippers are using .MKV with Xvid for video, HE-AAC or .AAC for audio... .ogm with vorbis audio are realy good too. lots of times your also run into .ac3 being used for audio, i think cause its less lossy(maybe im not an encoder).
u can prolly find well explaind info, by searching for ex.- noob guides or Vid Basics for beginners.. at one of these sites..