WMP versus iTunes. What I like about iTunes is it has its own Music Library where it stores its files, "if" the music has been added correctly (ignoring the LW playlist that shows up in the program.) Whereas WMP is a playlist player. It plays the files from wherever the file was added from. So should you move the file, WMP won't be able to find it. Ideally music should be moved to My Music folder before addiing to WMP player's playlist. But obviously everyone has their own preferred approach.

Disadvantage of iTunes is the basic program does not have ability to play mp3Pro format (patent format for smaller bit-rate type mp3 files), Ogg Vorbis, or a few of the other patent formats such as Real files. There are 3rd party plug-ins available that can help there though. And for viewing video, it only imports mpeg 4 and H.264 format (an advanced mpeg 4 format.) Whereas with WMP, you can get 3rd party plug-ins/codecs to help play various video file formats.