I had an Alienware M17X when they first came out with them.
$2300 (circa 2008) for a 17" laptop, Windows Vista (Win 7 free upgrade code), 2x Nvidia GTX260M graphics cards in SLI, 4Gb RAM, 2 500Gb HDDs (in RAID, so you only get 500Gb anyway). I forget the CPU specs. It was an Intel Quad-Core Duo I believe (9000 series?) 2.26ghz clock.
I played anything from COD to Arma 2. Functioned well. The screen (1440x900 IIRC) was a TN panel, but the best TN panel I have ever seen. It lasted me from 2008 to March of this year, until I built my own desktop. Never really had any problems with it. Everything was upgradable.
I never did upgrade it though. I didn't feel like spending $800 for newer (but still not the latest) graphics cards. CPU could only be upgraded to Intel i5 (newer versions of the M17X could be upgraded to i7). RAM was even upgradable.
Alienware makes a decent gaming laptop. Also, check out ASUS's ROG series gaming laptops.