DX vs. FX and D7000 vs D800
I bought a D90 two years ago and a 35mm f1.8 lens after taking a film photography class and moving into a digital class. After many photography classes later as well as Creative Suite training... I have decided to work with photography professionally.
My D90 has been great, but as I take this into the more professional realm, I would like a 2nd body... especially one that handles better in low light situations. I am looking at either the D7000 as a 2nd DX body, or the D800 FX. Obviously if I go with the FX, my lenses won't be interchangeable, but I imagine I will upgrade the D90 to an FX eventually as well. Does it even make sense to have a DX and an FX.... should both cameras match?
What are the differences between DX and FX anyway, especially in relation to more professional work? What are the differences between a D7000 and a D800? What about the upcoming D600... can I get some info on that?
I am wanting to provide a wide range of photographic services including portrait (outdoor and indoor, but I do not currently have access to a studio), small event (100 people or less), children, pets, live music.... and I am also really into fine art and will be shooting that on my own.
Any input is appreciated, thanks!