Nikon Flash Dilemma: SB-400 or SB-600?

My husband and I are thinking of buying an external flash for our Nikon D40. It's a great DSLR and we're quite satisfied with it, but we both think that an added flash would definitely work wonders for our indoor and low lighting photos. We rarely use the built-in flash of the camera since we don't like the results of the photos that come out using it. Now, here comes the dilemma... should we buy the SB-400 or the SB-600?



I have been trying to read reviews but they are conflicting and now I don't know what to think. I think that the reviews at www.kenrockwell.com are quite helpful but I've read other opinions at forums. We're leaning towards buying the SB-400 due to it's very small size which would be great to match the small body of the D40 and of course it's cheaper price. But it can only be bounced off from ceilings since it cannot be tilted sideways which would make it impossible to use for vertical shots. The SB-600 looks very bulky and big to me. But it does have more advanced features than the SB-400. Oh, I really don't know. Any comments are very much welcome, especially coming from those who know more about these stuff than I do. :)