While the final version of Firefox 3 will supposedly be launched in June (at least that's the latest news from official sources), as an avid software tester I can't keep myself from testing every single beta that comes out before the great day arrives. On the downside, this means that my Firefox installation may end up being a total mess: running different versions of the same program is never a good idea, and even less in the case of Firefox which I use to work on a daily basis.
If you can't wait until the final version comes out, but at the same time don't want to run any risks with your current Firefox version, use the portable Firefox instead. This special Firefox edition can be run from a USB device - or from your computer itself, without having to install a single thing. In this way you can take a sneak peek at the new exciting Firefox 3 features without compromising your previous installation and therefore your bookmarks, saved data, user profile and so on.
Now that you've managed to test Firefox 3 without ruining the good ol' Firefox 2, what about extensions? Most of them may not be compatible with the latest beta yet so you're probably wondering if there's any way to make them work. And the answer is yes: it's called Nightly Tester Tool, an extension that's been especially developed to make your old extensions compatible with the latest Firefox 3 beta versions. Of course, this is no magical cure for all extension incompatibility issues, but I must say it worked for me perfectly fine. Nightly Tester Tool also adds some useful tools for beta testers, such as a built-in screenshot app, direct access to the Profiles folder and a log file analyzer.