LOL , I'm going through something similar , Just a lower starting point .
I have the Rebel XT and was looking at the 30D , 5D and the 1DMK IIN .
Man theses are hard decisions . I've been doing some reading on line about the Pros and cons of theses cameras . I'm a complete rookie so these are just comments I'm understanding from other people .
The 5D : The bigger files help with the definition of the files . And larger copies.
The 1.0 crop gives you true wide lens capability , But limits your telephoto use . When using telephoto , the longer lenses create vingetting ( spelling ) and soft edges. Also with macro and telephoto to get the same DOF as the 1.3 or 1.6 crop you need to raise the F number up .
The focus speeds are very good but the 1d are still faster , and the 1D still has a faster FPS .
From this I get the 5D has better portrait and landscape capabilities with bigger and better defined Images .
The 1D MK IIN : Focus and FPS are still the best for speed. The 1.3 crop gives you better telephoto and macro use . with the lower f stop for the needed DOF , you get a little more low light capabilities .
So I think the 1D MK II N gets the nod for wildlife and sports .
I know you guys have much better experience so please , please correct me If I misunderstood what I read .
Not to completely highjack ( sorry if it offends you , just PM me and I'll start a new thread ). For me the 30 D is still an upgrade from the XT , and can't figure out if the way more expensive bodies are worth my rookie status and I should wait until I learn more down the line .