5.x versus 7.x

Hi all - We're currently in the process of emerging from the stone age and evaluating a move from 5.x to 7.x. I've read through all of the sales-oriented stuff I can handle, and conducted some basic tests to make sure everything functions, but I'm still lacking some hard facts. Maybe someone out there with actual experience can offer some opinions. I'm trying to determine major changes between 5.x and 7.x - mostly in the area of performance. I'm looking for things that the small scale tests that I've conducted can't really shed too much light on: 1. Hardware requirements - Higher for 7.x? Should I plan for more memory overall, per process, etc. 2. Multiprocessor vs. Single - How do the added parallel processing feature perform, and is performance seriously impacted on single processor machines? How about slower speed processors? 3. Operating Systems - What experiences have you had with Solaris 2.5.1/2.6, Dynix/ptx4.2.x, and AIX 4.2 - has anyone found one to fall a little short? Anything is welcome. Thanks in advance. Ben