This would go better in Computer/Technology Discussion...and as it seems like there's no active thread like this there, I'll go ahead and move it. :)
To answer the question - I use Firefox as well. I've tried using other browsers, but I've just never been able to like them as much as I like Firefox. I think part of it may be because it helped to save my old computer for a while longer - I used to get blue screens almost every day, though once I started using Firefox I never got one again (until the computer died, anyways). And I just never found any reason afterwards to switch to another browser, even one with tabs as well. Eh.