So I just got an Alienware M11x notebook after much deliberation, and while Dell took a comically long time to get it to my door, my initial reaction so far is: Awesomesauce indeed. I've been using it for several days, and just as I hoped, it can run both Second Life and Blue Mars at optimal levels -- this on a machine that cost under $1000, after an upgrade to 4 gigs of RAM. Getting used to the notebook's reduced size, which is three-four inches smaller than my last laptop, took some practice. (And some squinting -- I had to increase the font size on Facebook.) For New World Notes readers, however, the verdict on 3D worlds is good: I can run Blue Mars pretty well with all the settings turned up full (but performance is better at the midrange), and still more impressive, run Second Life with dynamic shadows enabled.
This is Second Life running in Imprudence, by the way; I'm not sure how shadows perform in SL Viewer 2. And these aren't just dynamic shadows that show up but then slow the world down to a crawl -- my frame rate only dropped a little bit. I'm far from a hardware expert, so do your own additional research, caveat emptor n' stuff, but if you are looking for a new machine that can handle 3D worlds, give this one a look. Also: Black matte finish! Red glowing keyboard! Chassis like a Stealth bomber! These are the things that make my geek propeller spin.