Ok, I'm officially a Firefox fan boy. For years, I used IE on the Mac and loved it. When it started to get sluggish on OS X when compared to IE for Windows, Apple turbocharged the open source project KHTML and released Safari.
I switched, but I keep IE around for those sites that don't work with Safari, either by accident of design (ActiveX centric) or intent (unwillingness to test or support Mac browsers). I still love Safari, but with Microsoft's rather nefarious plans to extend HTML farther with IE in Longhorn I fear Safari is not enough to staunch the tide of a Web where Microsoft controls the standards and other platforms are not welcome.
Then along came Firefox. I played with the betas and thought it was OK, but nothing spectacular. With the later betas and then the 1.0 release, Firefox became not just a lean browser, but a fast one as well.
Now something magical has happened. People are noticing. Firefox is actually taking market share from IE. Suddenly support for real opens W3C standards matter. For the first time there is a browser that uses the same engine on Windows, Mac and Linux. I can envision a day in the near future where all sites work in Firefox.
As great as Safari is, it's still Mac only. Even if the Mac mini doubles or triples Apple's marketshare, that won't have the force with web developers that Firefox could have in a much shorter time.