all about the glass. crummy glass crummy pics, smooth glass smooth pics.
You could probably do it, but a better lens would probably increase the sharpness and allow better quality large photos!!!
People are desperate to spend your money it seems... So I'll just suggest that the best investment will be time to learn to use whatever kit you end up using to it's fullest. Alongside the understanding techniques to shoot a good photo...
I did say probably...I have the kit lens and my nifty fifty is miles sharper and better in every way. Going to a 550D with 18mp will help, of course it will but imho better glass make more of a difference than better body...