For your type of photography, there won't be much/any difference between the cameras. What you will have to think about is getting a nice tripod, tripod head, and remote shutter release.
I'm new to the world of DSLR and I'm currently looking for a DSLR to get my foot in the door. I'm mostly interested in night photography and low light situations. Also, I prefer landscapes over portraits. Would you recommend a camera that is capable of delivering what I'm looking for?
So far I've looked at Rebel XSi, Nikon D90, and Pentax K20D. But, any suggestions are appreciated. Thanks