Help: Storing File Association

What would be the "preferred" way of doing the following.

Here's an example of what I would like to do. Say a user clicks on an .mp3 file, my program would execute first then perform some tasks on the selected .mp3 file, such as read the MP3 tag or whatever, then load the users default program that was associated with mp3 files...say winamp.

Basically what needs to occur is associating my program /w .mp3 files in the registry, but first I need to obtain the current program "OPEN" command associated with .mp3 files. This can be done programmatically, but can this be done /w Visual Installer or any other method?

Thanks,
Clif