File Association in Vista

If you find that a file is opening with a program other than the one you want it can be hard to find the file associations dialog.

1) Open Windows Explorer
2) Right click on a file with the extension in question
3) Go to 'Open with...'
4) As a selection you will see 'Set default program', select this.
5) You are now in an association dialog where you can pick a program, browse to a program of your choice, along with other options.