I am currently running Windows Media as my default player for all mpeg, mov and avi files. I have 3 questions

1., How do you change default players

2. do most people find windows media to be the best player or have you had better experience with Real Player or a different media player

3. It seems that most .mov files are junk. Are .avi files usually junk as well?

4. the few .avi files I have tried to run, typically give me the the error code "One or more codes needed to play this file cant be found"..
What can I do in this case, and is there a way to see if it can be viewed on an alternative player or possibly convert the file to get the proper code

Thank you in advance