I agree with everything already said. I would just add these thoughts:

Poser 4 or Pro Pack is less demanding in the memory department than Poser 5, but I think you want at least 512 MB in either case. RAM's pretty cheap nowadays, but you'll need to check your system specs (OS, motherboard, etc) to see how your memory is setup now and what your system capacity is. The websites for the big memory makers (PNY, Kingston, etc) have databases you can access to see what the options are for your exact system, so you may to check them out.

The processor speed you have seems perfectly adequate, scene loading and renders will just take a bit longer than if you had a 3 GHZ system.

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