Lemme chime in here about P5 functionality on older comps from my experience. The situation:

When P4's were past the 2gig point, bout I think 4 - 6 years ago, I set out to build the best obsolete P3 I could to chase cheap parts. Total expenditure turned out to be $1,200.00 for hardware alone:

MSI motherboard with 1.2gig P3 cpu ceiling and 1.5gig RAM ceiling at pc133 busspd
1.5 gigs of DIMM RAM (3x512 stick)
1.13gig P3 Tualitin CPU

P5 cant do much on this machine at all. Multiple chars choke not only the firefly but the P4 renderer as well. Until I can sink around half a grand into a P4 system - and unless im working with at least a gig of the new DDR RAM I think im really gonna notice a difference from the 1.5g DIMM speed im used to, so push that half a grand figure up a respectable bit! - I really am "stuck" with ProPack. Add the complication of my car's recent dropping of its transmission and my prospects of the P4 system get even more back-burnered :/

I think many users may not realise just how poorly P5 performs on even the most maxed out of the obsoletes out there :(

I dont see myself getting rid of PP even when I do finally upgrade. Its so intuitive and easy to set up a complex scene. I have been able to successfully do small projects in cloth room of P5 to export to PP for texturing and rendering and I am completely impressed with what ive been able to do with P5. Im very eager to learn it more completely, as well as newer versions!! I just have no choice but to be patient about that at this point though :)

Logan