One of the biggest complaints a Firefox evangelist encounters is "it doesn't act or feel like browser X." Internet Explorer users complain that Firefox doesn't look like what they're used to. Opera, Safari, and Netscape users complain that it's missing many of their favorite features. And the social networking gurus point to the powerful social networking features Flock boasts and Firefox lacks. However, all these users overlook one of the most powerful features of Firefox: support for third-party add-ons, which can make emulating the features of other browsers extremely simple.
One of the most popular browsers (and the most popular browser for non-techies) is Internet Explorer (IE) 6. When you're converting relatives to Firefox, IE 6 will most likely be what they're used to.