I have no interest in video so I can't comment on that but as the owner of both a 550D and its grandfather, the 450D, I can recommend it for stills photography.
As noted above, we really need to know a little more about your photographic interests before making a firm recomendation. If you have any interest in wildlife then the 550D is an excellent camera. If performance in poor light is an issue then you should seriously consider a Nikon.
The standard advice is go down to your local Jessops / Jacobs / other pusher and fondle the stock. There are people who love the handling of Canons and hate Nikons and vice versa.