Current Adobe Lightroom/Photoshop practical system requirements

[atxcyclist]

I realize that these can more-or-less be looked-up on Adobe's website, but they are vague. My father is looking to do some photo manipulation/touchup with high-resolution scans of film negatives, and would like to have a dedicated desktop in his work-space for it, since his laptop isn't always there. I've been considering just donating some parts to the cause as I have a ton of stuff sitting around, but I don't want to bother if it's under-powered for the process. Currently I have:

 

-Dell OEM mobo with a Q9505 and I could put 8gb of compatible memory in

-Dell OEM mobo with a Phenom II X6 and 8gb of memory

-Athlon 870k in a nice board with 16gb of memory, don't want to give it up if the other setups would be sufficient

 

I also have an older HP slim desktop with a Phenom X3 and 4gb of memory, could probably put 8gb in there but no more. Is more than 8gb nescessary for this software with 400~mb scans?

 

So, what are other people using for this software and what are your thoughts? I use GIMP and I don't do any work on my photos so I have no experience with it.