Firefox has gained decent market share over the past couple of years. Now Microsoft is making an attempt to recover that market share with Internet Explorer 7. Information Week has an editorial regarding the issue.
Like Barbara, I switched from Internet Explorer to Firefox on my PCs. A main part of my decision was being compliant in web standards. Another reason for me is I started using Macs more and more and Firefox was a great browser for both platforms. As I have said before, I get a fairly consistent browsing experience across platforms.
Spyware over took my computer every time I attempted to use Internet Explorer, which is much reduced when using Firefox.
Internet Explorer 7 looks to integrate similar features as Firefox and looks to improve over previous versions. The thing with programming is programmers tend to be focused in a technical mindset. What makes things easy for the user is sometimes overlooked. As more and more people get used to a new browser and they are comfortable using it, they will be able to make an educated decision on browser choice.
I think Firefox will continue to gain market share from the popular Internet Explorer browser. They have a much greater audience to try to find switchers and for the most part I think they have done a good job so far. So what browser do you use? Add a comment and let me know.