Our solution will replace the entire PB2K computer with brand new parts. The question is would people rather purchase the complete solution from us (motherboard, ram, ps, etc) or only the hardware/software we make? If we sold just our parts we would specify a list of compatible parts but it would require that the user has more than average techniocal expertise. If we sell only the parts our support would be somewhat limited due to possibility of user error.
I suggest offering both. There are surely going to be lots of people in both camps. Personally I have so many CPUs laying around here, I probably already have the hardware needed and would prefer the partial kit. But lots of people in this hobby will want the easier to install option. Also with that option you have a little bit more opportunity for profit.