@blazorthon: Firefox is based off the Gecko engine, which powered the Mozilla Suite which came out in version 1.0 Final at the end of 2001 - so, it IS actually more than 10 years old. IE6 came out in 2001 - only IE9 managed to really break away from its engine (IE7 was only a major bug-fix, IE8 still retained the Javascript engine and a bunch of parser glitches). Opera was at version 5 or 6 by then.
In fact, since Webkit is a fork of KDE's KHTML component (the fork occurred in 2002; Konqueror, which used KHTML for HTML rendering, was a quite advanced web browser in its own right), even those can be considered to be decade-old.
However, I shudder at the extra traffic and CPU load generating a preview of a page will entail. And, on rich web pages, this type of components will mess with the event listeners put on the links...