Hi if you're going to take a Canon entry go straight to the 500D. It's quite a lot better than the 450D and almost the same price.
I took quite a few photos with it and it is pretty good entry level. You can see my 500D shots here:
Canon 500D Martin Soler Photography
I was pretty happy with it until it was stolen. But that's a whole other story.
Only trouble that I seemed to have was noise. But I never found out if that was because of my inept use or if it was the camera.
I currently have the Nikon D300 and I think the pics have a better quality overall. Though lower mega pix. You can see my D300 pics here:
nikon d300 Martin Soler Photography
See for yourself if you can notice the difference. On Nikon try the D90 it's the 500D equivalent.