If you do not have a file changing program. But  you what to change some/all of you music files to MP3 form. This is what you do.


First you go to the folder that you have you music in.
Once there you click on View and then Folder Options.
A new window will open.
Then you click on the View tab at the top.
Then in the advanced settings part of the window Uncheck Hide file extensions for known file types and click ok.

Now at the end of every file name there is the name of the application that opens the file. 
 Of the music files you want to change to mp3 just right click on the file.  
Then click on rename.
The name of the file will then be highlighted.
While the file name is highlighted delete everything after the dot.
And put mp3 in its place. 
When you have done that hit enter or click off the file to make the renameing final.
A warning will then pop up. Just click yes. You can always change it back to what it was before.
Do this to all the files you want changed to mp3.

After all of that.  Go to View.
Then folder options.
Again a new  window  will open.
Then click on the view tab.
Recheck the Hide file extentions for known file types and hit ok.

The file names then lose the dot and the application code.

P.S.  Remember the code of the file before you changed it incase you need to change it back.



EXAMPLE:

Song Name.
Aerosmith - Jaded

Do everything in the first Paragraph then it changes to

Aerosmith - Jaded.viv  (or any other sound code(.ps .class or one of many others)

Do everything in the second paragraph and it will change to

Aerosmith - Jaded.mp3

Do everything in the third paragraph and it will change back to

Aerosmith - Jaded

Then you double click on it and see if it works.


Good luck.