You could install OpenSolaris inside the free VirtualBox. Maybe this would be your best bet?
Install VirtualBox on top Windows XP. Install OpenSolaris on top VirtualBox. Then it doesnt matter if you screw up your OpenSolaris install, nothing can happen to Windows. And you dont have to partition your hard drive. Just use Windows all the way, until you get familiar with OpenSolaris. Then, you can install OpenSolaris on a partition. But first you need to learn OpenSolaris and toy with it. Do that inside VirtualBox. As for upgrading, just use the "Update manager" to upgrade your OpenSolaris to the latest build, and it will automatically install latest Firefox for you. -- This message posted from opensolaris.org