I agree the noise control for 450D is not very impressive, especially for night photography.
In night photography it is always best to use a tripod instead of pumping up your ISO.
Do correct me if I am wrong: One must understand the advantages/limitation of their equipment first and know how to use them to their fullest potential. Personally it only make sense to upgrade if you feel that your current equipment is holding you back and only changing it would resolve it. :think:
It's true that profession equipment make it easier to get your result, but if one think that just by buying the top-end camera would magically turn their shots into masterpiece then I have nothing to say. :what: