natskis wrote:I'm wanting to shoot some weddings and also sports
You've said the two magic words. =D Get yourself a 7D (or an old 40D if you just want images). You can't afford buffer speed when shooting any of the two. But with that being said, buffering speed is also quite a luxury.
But with that being said, its up to end user, will you use the 550D in 5 years time? what will the 550D be doing in 5 years time? do you think you'll upgrade in 5 years time? waht will serve better purpose for you ? all in all.. its a vast question, but in terms of the benefits of a 7D... put simply.. You'll know how to use a pro series and pick up using a pro series quicker than converging straight from a 400D.
thats my advice anyways.. but its also my opinion =D GL