Ok, that immediately answers all the questions

The Forest Superior is HUGE. On my PP2012 it takes 3GB upon load. The killer here is the number of polygons - it is wel over 4M polygons - which is 20 times as much as a V4 figure. There are several tree sections - each one well over 400K polygons and then the grass takes 600K polygons. I think you get the picture

You will not get that one into 32bit poser

You reduce on textures, but that won't be enough