tools >> option >> general >> Home Page - Location(s)
and enter the addresses you want to goto seperated by a pipe. e.g.
Also i might be behind on this but i just noticed the re-deisgn over at Mozilla. I know they've been working on this for sometime and it looks like its paid off with a more professional and clearer look. They've also got some Atom feed for their News, weblogs, and announcements.