i was and still am facing this problem. 430EX or 580EX for my 450D? people told me 430EX will be good enough. unless shooting events (correct me if i'm wrong). and you're bound to upgrade your camera one day right? i believe you will go for a 580EX or a newer model (if there's one) after upgrading too. at that point of time, 430EX will come in handy as a slave flash.