The only thing that will really make image processing faster is ... the processor (CPU). Photoshop will probably utilise dual cores
, but expect to pay the $$$ for them. RAM & HD space will help, and probably no less than 1GB of RAM, but at the end of the day when you're doing serious image processing, 90% of what counts is your CPU.
I guess de-bayering at 2.6 vs. 2.8 will reduce quality of the end result, but if the difference is on a 'who cares' scale, then it's probably not a big issue.
Cheers
Hoopa