ATI graphics/worstation APPS/firestream vs cuda

I am quickly finding myself caring less and less about gaming (I haven't gamed at all in about two weeks, and the last time was only for about an hour), and I am more interested in raw power for experimenting and tweaking around with various things. I want to have a powerful machine for powerful tasks, like video rendering and photoediting, not that I do any of these things, but I might. I have a second HD 4850 that will likely be coming back very soon from my RMA, and I will be going back to crossfire then. However, I am musing with the idea of trading for a set of nvidia cards possibly sometime down the road. I want to know which cards work better at workstation apps.

I am also extremely interested in firestream and CUDA. I know that CUDA can be coded with simple C, but I don't know if it is quite so easy to do so with firestream. I was wondering which is overall better, or what the main features of each are.

Links to benchmarks would be great