Mentioned in another thread was the probability that Tiger and Leopard can run together at the same time. Tiger supports my photographic post processing Nikon Capture NX. Leopard doesn't yet according to Nikon support. Can I run both OS's on a Mac Pro which I have just ordered? Would I be better off removing Leopard and using only Tiger until any bugs are worked out. This MacPro is going to do all my post processing work flow. I need to know what I need to do. I have no fear of the OS, whichever it is, I just need to understand the basic question asked. My livelihood depends on it. I used to love Mac but went to PC when finances were tight. I am back to Mac in a big investment way. Thanks to all of you for this great forum.