you need to download the mozbackup utility and run it.
This will save all of your bookmarks, passwords, extensions, and all the other addons and stuff you've customized to your FF 1.5.x installation. http://mozbackup.jasnapaka.com/download.php
You can then donload FF 2.0.0.2 and install it as a new installation, and retain your 1.5 installation for the time, just to be safe.
Everything you saved with mozbackup SHOULD be automatically brought into the 2.0.0.2 installation with the new installation wizrd that comes with firefox 2.0.x
the mozbackup will create an achive of your addons and other options and setting for FF1.5
After you install FF2.0 you can use mozbackup to transfer the archive into 2.0 and you'll almost seamlessly transfer to 2.0
Well, coming from a former Soviet block country, I hope it doesn't come with a virus.
Nice utility. It could really come in handy considering that I force my computer customers to use either Opera or Firefox.
Excuse my off-the-cuff comment; I was snarly. I've looked further at the program and it seems to be able to perform a comprehensive backup.