Dave, Netscape is always a bit behind Firefox.
They use the same rendering engine (Gecko), but it always takes some time till the Netscape people adapt it to their browser.
This is also the case for security updates.

Firefox is just a browser, if you want email as well, use Mozilla or Firefox + Thunderbird.

Susan, when you mentioned mapquest I first thought you might have no Java plugin as most map services use a Java applet for displaying maps - but mapquest works even without Java, Flash and Javascript.
All pictures at levenger.com are displayed in Firefox 1.0 and Mozilla 1.7.3 (got no Netscape 7.2 here).

Stilly, Firefox doesn't have some of the scripts for secure pages that my bank wants to use when I log on, so I have to go to IE.
You probably mean: the web designers at your bank are unable to do their job.