I have been using Firefox for almost 1 year. Starting with a pre-release version to the current release 1.0. Unless I'm at the MS update site or a couple of financial site that require IE6, I use Firefox exclusively.
I am so impressed with the features, ease of use and increased security/privacy features of Firefox, I have set my IT staff lose to convert my networks 50+ workstastions to use it.
Tabbed Browsing
Increased Privacy
Better Security
Faster loading/browsing
Why would anyone us MS IE?