You a Nikon fan claire?
I'd recommend brad a Canon 350D in that price range, but I much prefer Canon.
I have 2 Nikon SLRs, 35mm and a DSLR, and love them both dearly.
I've used a Canon 350D and as I'm used to Nikon's it never felt right in my hands, and obviously the layout of all the buttons/dials is unfamiliar to me, felt all alien
I'd say there's only minor differences in what they can do at this end of the price range, anyway, Canon's are usually a bit cheaper, though. People talk all kinds of crap about lens coatings being better on one than the other, and low-light and ISO reponse, but to me, it's all about which one feels right in my hand and can do what I want it to.