Give Firefox 3 a whirl without messing up your FF 2.x install. Here's how..
If you are afraid of messing up your current Firefox install but want to take the new Firefox 3 Beta for a spin try installing a copy on a USB drive using Portable Apps.
Mozilla Firefox, Portable Edition 3 Beta 3 | PortableApps.com - Portable software for USB drives
I've been using PortableApps.com to take my Firefox and Thunderbird with me to work and when I travel without my laptop. It's great! They even have a portable version of putty so I can create an SSH Tunnel to a server and keep big brother from spying on me at work and blocking blogs and forums.
I'll post my comments and some screenshots for FF3 beta once I have a little time to try it out.