As a small side note, if you've been thinking about checking out the great Google Earth program, do so now. This Saturday we're going to hold a little GE 'easter egg hunt' which should be both informative and fun. It should, in turn, spawn an interesting post of the collected results. If you want to join in, it'll be helpful if you already know how to use this most intriguing of programs.
I'm surprised I haven't blundered across this before now, but check out this cool Firefox update page. I needed pretty much everything on the list.
Along with Adobe Reader for PDF files and the ubiquitous Flash, I recommend the QuickTime plugin for the occasional QT video and Java for older sites that are using Java instead of Flash for various special effects.
As far as Firefox's various problems with Flash, it appears some of it's been ironed out recently. Both have come out with updates since my post on it a month ago and I haven't seen any snags since then. If you've been having problems, I suggest running the Flash uninstall program before updating.
On the subject, the other common Flash problem is running into a 'Currently unavailable' message when trying to play a YouTube video either from the main site or from a page with an embedded YouTube video. This is YouTube making a little experiment with selected members using a new viewing protocol called 'HTML5', and apparently they don't like you using that old, hackneyed Flash player on their precious videos. The solution is to go here and click on the link at the bottom to opt out of the program.