For Sculpting - as much RAM as possible.

If self building I'd say go with an e2160 from intel - overclock it like mad and then use the money saved versus a more expensive processor on RAM and gfx card.

Take a look at Toms Hardware for an idea of how far you can push these little babies....

http://www.tomshardware.com/2007/09/12/pentium_dual_core/

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Toolset: Blender, GIMP, Indigo Render, LuxRender, TopMod, Knotplot, Ivy Gen, Plant Studio.