The Rebel XTi is the USA version of the 400D, but it would not have the European warranty on it, so if you have a problem Canon UK would not be interested. See here -
http://www.dpreview.com/reviews/canoneos400d/
Got my 400D off the Canon outlet store on ebay, very happy with it so far, not had chance to take it outdoors yet. But the indoors stuff has been fine.