Setting default browser

To make Internet Explorer the default web browser,

In Internet Explorer -> View menu -> Internet Options -> Programs
Enable
'Internet Explorer should check to see whether it is the default web browser'



To make firefox as your default browser

Go to Tools -> Options.
under general tab, check the check box for "Firefox should check to see if it is the default browser when starting".

or you have a button "check now" if you click that you will get an alert if firefox is not the default browser. if you click yes, then it will become default browser.