This Message Forum is no longer in use
Please use the new Bravenet Help Forums FOUND HERE
Firefox is generally standards compliant, IE far less so. If a site looks good in IE but not FF it generally means that the webmaster has put in some IE specific, non standard, code.
I couldn't see any differences between Opera, Explorer and Firefox that were big enough for me to notice. What Peter says is true, if you want an answer that does not contain the word "generally", you need to be more specific than "not properly".