Scruffy - welcome to the forums! You have 2 great options here, I don't think you could go wrong either way. Though, I think you might be a little better off with the Canon EOS 5D. The full frame will give you a better lens resolution, as well as a larger viewfinder. An all around benefit, and a particularly great benefit shooting macros. And yes, for what you are shooting you definitely want a macro lens, heres a lens at a solid 65mm with 5x magnification - click. You could blow up a grain of rice to a 13x19 print!!! ;) You may also want to invest in a macro flash ring like this.

Hope that helps.