Running Firefox 2 and Firefox 3 in the same machine

When doing website development, sometimes we need to see the page behaviour on both Firefox 2 and Firefox 3 for backward compatibility.

Refer to the following articles on how to setup both Firefox 2 and 3 running on the same machine.

http://blog.andreloker.de/post/2008/06/Firefox-2-and-3-side-by-side.aspx
http://www.command-tab.com/2008/06/18/how-to-run-firefox-2-and-3-simultaneously/