Welcome to PR Zars, you will find lots of information on here, i know i did

what i would do is go with the canon, you cant go wrong with a canon.
and im not just saying that because it is what i use but all my friends that have them have had nothing but positive things to say about canon.
even if you went with the 350D it is a great starter camera and cheaper then the 400D
with canon as you mentioned there are tons of lenses out there for your camera (canon, sigma and all those)
but either way 400d or 350d you wont be buying a bad camera!
good luck with your search