Rob, if you're going to use Reality/Lux you don't want to go with AMD. A three-year-old dual-core Intel out-performes a top-of-the-line 8-core AMD chip. Neither AMD nor Pret-a-3d have any idea why (and they're beating their head against it right now). For rendering with Reality you'll want as many cores as you can throw at it. I have three, 8-core i7s that I can render with, which gives me a good deal of turn-around (1.5k samples/pixel in about an hour for a low-object scene). On the other hand, 8 gigs of ram is sufficient, but you'll need more than that for Daz, if you want to do high-object scenes.
If you're just using Daz 4.0 for rendering a quad-core i3 should be sufficient (my old dual-core gaming laptop can Daz-render with advanced surface shaders in about five minutes).
If you're just using Daz 4.0 for rendering a quad-core i3 should be sufficient (my old dual-core gaming laptop can Daz-render with advanced surface shaders in about five minutes).