Ok i tried out I.E 7 yesterday, i used it for about a day and its crap to be honest, was back on Firefox straight away i didn't have any Gmail notifier so if i got email id have to actually go to the website to check it and all my most used websites ive got across the top of the browser i didn't have on I.E because i couldn't place any sites there, and lastly I.E doesn't have an inline spell checker, not that i desperately need it like some people but its nice to have for those really long words you never use etc

So thats the main reasons i use Firefox and will continue to

EDIT another thing i like about Firefox is the smoother scrolling through website pages, although I.E 7 has smooth scrolling its no where near as smooth as Firefox.