EDIT: I had one more question. Does anyone know which AMD Driver introduced support for the Radeon HD 7970 (I assume I'll just have to experiment with the drivers that AMD has released)? I'm going to add that into my computer soon.
I went through some trial an error with my first 7970 and I think 12.3 was the first version I found that worked. 12.4 is more stable, though. I have a rig with 5850s and 7970s and 12.4 (and the SDK that came with it) was the least 'problematic' to run both.