System for Post=Proc

I'm a nightmare of indecisiveness. I have a super old Dell Desktop, maybe 6 years old, that I maxed out when I bought it, so it's still running as well as can be. But I'm about done with it, and need a laptop (I use my work laptop for around the house so I'm not stuck in my office at a desk).

Anyone have favorites for running programs that eat up RAM - primarily Lightroom? I'm a geek, I know every Lenovo, Asus, MBP/MBA option out there. But I'm torn, constantly, about spending a bunch of cash on a bulky Laptop like a Lenovo W530, which would no doubt do the trick but not be a ton of fun to travel with (and let's face it, I'm a tech geek so it's not the prettiest). Then there's the new Asus U51vz, which is crazy expensive, but lots of power in a small package. I'm not an apple guy, I'm a photographer who doesn't like Apple, I know...

Any ideas for something without the cost of the $2000 Asus U51 (or a MBP), but that still can power my Lightroom and isn't 7 pounds? Am I stupid in thinking that something like a Zenbook 32VZ or Carbon X1 isn't enough juice? Or would those be perfectly fine? I'd love to hear current systems running Lightroom 3.x or 4, and how the performance is.

I really, really hate waiting for 3 hours for my 1:1 previews to populate in Lightroom... Thanks all.