Windows: Play It Safe with Self-Contained Portable Firefox 3

If you want to use Firefox 3 without losing Firefox 2 or touching its settings, you want the portable Firefox 3 beta application. This standalone, self-contained version of Firefox isn't just for thumb drives. Save it to any folder on your computer (I prefer one called Firefox 3b5 on my desktop) and it creates a whole new user profile and runs completely separate from Firefox 2. One catch: you can't run Firefox 2 and portable Firefox 3 at the same time.

Download the portable Firefox 3 Beta 5 for Windows

When you run Firefox 3 portable you'll start out with a fresh profile that doesn't have your extensions, bookmarks, and homepage set. Instead of going through all the work of setting those up again, you can copy your Firefox 2 user settings to Firefox 3 portable. Here's how.

1. First, make sure NO versions of Firefox are running at all, but that you've run Firefox 3 portable at least once.
2. Navigate to the Firefox 2 profile folder you want to copy to Firefox 3. ( most likely it will have the word "default" in the folder name.)
3. Copy that entire folder and paste it into the Your-Firefox3-Folder/Data/ folder.
4. Rename the existing profile folder in Your-Firefox3-Folder/Data/ to something else (like profile.bak).
5. Finally, rename the profile folder that you just copied (something like nsm1chqs.default) to profile.

Now, launch Firefox 3 portable, and you should see all your Firefox 2 customizations there.