File Types tab missing -- NirSoft to the rescue

Windows 7 and (worse) Windows Server 2008 no longer provide a GUI to fully edit file type associations.

Earlier Windows versions (e.g., XP) allowed you to edit this via the Windows file system explorer menu Tools > Folder Options... dialog, the File Types tab.   There you could define which program is associated with each file extension:

 

If you pushed "Advanced", you could then view the various file operations that could be performed:

 

And you could redefine how the programs were actually invoked to perform each action:

The "File Types" tab is missing in Windows 7 and Windows Server 2008.

To the rescue is NirSoft with their FileTypesMan utility.