If I were you I'll get the 500D instead because it has a Digic4 processor which translates to better pictures. I mean you are buying new why not spend a little bit mroe for something that will help taking great pictures in general.
Yea in the long run you'll probably be better off with Digic4. More importantly, the lens is more important than the camera body itself. Don't get me wrong have a good camera body is a plus too.
Oh and since you're doing mostly landscape you might want to consider a tripod and maybe lens filter.