there are many reasons i use firefox. the #1 reason is probably the extensions. e.g. Download Statusbar, NoScript, and a few others. I also use the portable version of firefox from PortableApps.com because I like how it organizes the program and profile (bookmarks, cookies, passwords, extensions, etc). It makes backups easy, and it lets me configure multiple profiles easily. I like the bookmarks toolbar, the search toolbar, the find feature, and ease of customization. I also like being able to go into another OS (linux/mac) and having a familiar (same) browser. I trust the Mozilla foundation more than Microsoft. Firefox is also updated more often. and Opera is a very fast and nice browser, but I like firefox more. On a fast and well mantained computer the speed differences between IE/Firefox/Opera are insignificant.