Something else to consider is the supplied lens with both of those cameras. When I bought my 1000D earlier this year, it came with the 18-55 is lens, the 450D had the same lens.
I have noticed recently on the high street that the 1000D now comes with the older, non is 18-55 lens which used to be supplied with the 400D.
This certainly was introduced on the quiet & is very sneaky & mean from Canon imo.