Here is why I disagree. For one, under sounds, if you select one you can then click on browse and all will open and you can go to the exclamation one and change the extension. Then in a month when you want to change it back, you know which one it is. In fact, you can change the name to Windows XP Exclamation.saveac_message
Now, I tried the method you suggested (works fine), but I forgot which .wav was associated with it. Now my close program sound is TaDa! I will now have to go through all of them again AFTER I go to another computer and find out which sound file it is.
Of course, I could be missing something.
