FireFox 2.0 is an evolutionary rather than revolutionary, upgrade to FireFox 1.X. But that's OK with me. Evolution is good, and revolutions can be bloody. Here are my top two reasons to start using Firefox 2.0:

• Integrated spell-check. This is a compelling feature for folks like me that have home-grown blog editors that lack spell-check. FireFox 2.0 automatically spell-checks multi-line text boxes. I've even gotten in the habit of making single-line text boxes into multi-line text boxes, just to take advantage of this feature.
• FireFox 2.0 finally renders text in <PRE> tags correctly. In previous versions columns didn't properly line up. Since I use the HTML <PRE> tag to display source code, this is an important bug fix for me.

Download Firefox 2.0 from mozilla.com.

PS Plenty of invaluable features have been in Firefox since version 1.X. Click here to see my favorite 1.X features.