Hi!

I'd definitly take the dual-core machine. On my Thinkpad with Intel Core Duo (T2400, 2x 1,8 GHz) I'm almost twice as fast on rendering/raytracing images with Blender compared to my AMD Athlon 64 3200+.

I recently purchased this laptop and it has been a joy so far:
http://www.newegg.com/Product/Product.asp?Item=N82E16834220124

There was a version with XP loaded instead of Vista - the Vista has been pretty much okay being that I got my Lightwave, Vue Infinite, XSI and ZBrush working on it (MOI of course as well) - there are just some apps (like my AfterEffects for one) that still aren't vista compatible yet so that can be a bummer...

I love the battery time - I wouldn't be surprised if I can't get 4 hours from it! I've yet to see the battery go down to half while using it - I'll have to see one day (on a plane or train trip somewhere...)

-Will