With as relatively few problems as have been found with Firefox, the fairly quick turnaround in fixing them (as Erik pointed out), the customization and ability to bend Firefox to your will, and not the other way around, as with IE SHOULD lead others to look for alternatives even to Firefox (in search of an even BETTER solution), but your failure to investigate the background to your "solution", Seph, will probably lead him to not only ignore your "solution", but to wonder if you would have been able to help him even IF you used Firefox.
Telling someone their problem is that they're using the product they're asking for help with doesn't solve it, and clearly he's chosen to give it a try. It's like telling someone the reason they're having their problem is that they're using Win98 instead of XP. It doesn't solve their problem, it simply tells them you can't help them, and have no interest in helping them.