Not a big deal, it fits here too.
I use IE6 mostly. The reason is a combination of the very low memory usage, fast startup, integration with explorer and my habit of clicking the blue "e" on the taskbar. Firefox is nice, I use it from time to time with certain extentions like video downloader and downloadthemall, but I prefer IE6 for the reasons above. I don't like IE7. The interface is just plain wierd.