ask yourself a few questions = what do you want to use your new camera for? what do you anticipate doing with it? will the bulk/weight affect how likely this is? etc. an example - my girlfriend chose not to take her nice canon dSLR on a two week hiking/exploring trip around Norway due to the weight of body + lenses, and also due to the fact that my micro (powershot A590 with faux-slr capability = you can control shutter speed etc and it only cost a few FTP points ) takes ok image quality as long as the light is good. And cos i refused to carry her dSLR on the grounds that i was already carrying a camera.

do you already know people with SLRs? are you on terms that means you would lend each other lenses? do you want to shoot movie footage? are you interested in macro work? landscapes? playing with a new toy?

nikon and canon have got a similar range. Most people have a bias towards what they use -> suggests that both brands are solid. I like the canon 550d a whole lot, but haven't bought one for myself yet.