All you have to do is to change the default association.
Type 'default' in the Start menu, and select "Default Programs".
When that Window opens, select 'Associate a file type or protocol with a program'.
From there you simply select the file type, and in the upper right of the Window select "default Program" which will give you an "open With" choice. If the app you want is not listed, simply navigate to the .exe location of the app you want associate the extensions to.
Or follow the above suggestions - all three methods will work