Need buying M18X opions

Looking to replace my Alienware M5750 (5 years old), with a refurbished or used AW M18X. Any experiences buying on used or refurbished?

I've identified about a half dozen I seriously am interested in. The main question is do I go for high end processor or high end graphics see my list and give me your choices. I used to be a big first person gamer (Doom, Quake, Unreal, Duke Nukem, Rise of the Triad, and Castle Wolfenstein) and I will probably pick up one or two of the newer titles. I will probable keep this system for 5 years as well. I do a lot of excel spreadsheet stuff and all the basic stuff. This is a desktop replacement, I sometimes bring to work for fun or having a second screen on a big project.

Intel Color RAM VIDEO SYSTEM HD
3820QM RED 16GB GTX660M (2) 256 SSD
3630QM BLACK 16GB GTX660M 128 SSD / 500GB
2670QM BLACK 8GB GTX580M SLI 750GB
3610QM BLACK 8GB GTX660M 750GB
3920QM BLACK 16GB 7970M CROSSFIRE 500GB
3720QM BLACK 16GB GTX675M SLI 256 SSD
3820QM BLACK 16GB GTX675M 500 GB

Processor Speed Pass Mark Benchmark
3920QM 2.9GHz 9149
3840QM 2.8GHZ 9023
3820QM 2.7GHZ 8811
3740QM 2.7GHZ 8573
3720QM 2.6GHZ 8404
3630QM 2.4GHZ 7768
3610QE 2.3GHZ 7690
3610QM 2.3GHZ 7539
2860QM 2.5GHZ 7240
2670QM 2.2GHZ 6099
2630QM 2.0GHZ 5631

buy the asus g series or the msi equivilent instead. dell adds about $300 on top of the price, and it is just a clevo with a top cover change so why pay the extra. msi adds things like a turbo button that overclocks and sets the fans to a nice minimum speed so it wont go quiet to loud + they have a nice steel series keyboard on some of them, and asus is just nice and clean.

for the parts i would do the 79xx graphics, and the cpu does not really matter but the higher clock the better.

Smaller list based on Zanzabar likes
3740QM RED 16GB GTX675M SLI 500 GB (7200rpm) BLUERAY/DVD/R-W
3740QM RED 8GB GTX675M SLI 500 GB (7200rpm)

3740QM 2.7GHZ 8573 <-- Pass Mark Score

Video Card(s) 3D Mark 11 3D Mark 06
GTX675M SLI 6407 31210

Well I found one that fit my specs and price, seller told me condition is perfect so I hit the buy it now.

M18X Nebula Red and priced at $2195.00

Processor: Intel Core 3rd Generation i7-3740QM Processor 2.7GHz (6MB Cache, 3.7GHz w/ Turbo Boost 2.0)
Operating System: Windows 7 Home Premium x64 & Reinstall Windows 7 Disc
Display: 18.4 inch (467.36 mm) WLED WideFHD (1080p) display (1920 X 1080)
Video: Dual 2GB GDDR5 AMD Radeon HD 7970M - CrossFireX Enabled
Memory: 16 GB DDR3-1866MHz SDRAM, 4 DIMMS
Hard Drive: 500 GB SATA Hard Drive (7200 RPM)
Optical Drive: Slot-Loading Dual Layer Blu-ray Reader (BR-ROM, DVD+-RW, CD-RW)
Connectivity:Killer Wireless-N 1103 a/g/n 3x3 MIMO for Gaming & Video
Bluetooth 4.0 10/100/1000 Gigabit Ethernet network interface adaptor
Sound: Integrated Analog 5.1 Surround Audio Support , Integrated Digital 7.1
Surround Audio Support (via SPDIF or HDMI 1.4), Audio Powered by Klipsch
Web Cam & Mic 2.1 Megapixel Certified Full HD Camera with dual digital microphones
Media Reader: 9-in-1 Media Card Reader
Keyboard: 4-Zone, multi-color RGB, 82 key keyboard with AlienFX lighting controls 5 user-programmable keys providing up to 15 distinct functions per application or game
Battery: High Capacity 12-cell Lithium Ion (97whr)
Power Adapter:330W A/C Adapter & Power Cord
Color: Nebula Red Anodized Aluminum

Input Ports: (1x) Security Lock port (1x) Line In Microphone 1/8"
(1x) RJ-45 Gigabit Ethernet IPv6 (1x) Mini-Display Port
(4x) SuperSpeed USB 3.0 Ports (1x) 9-in-1 Media Card Reader
(1x) eSATA 3Gb/s + USB 2.0 Combo port (with PowerShare Technology)
(1x) HDMI 1.4 Audio & Video Output (1x) VGA Port (2x) Audio Out 1/8" Ports
(1x) HDMI 1.3 Audio & Video Input Out (7.1 digital audio output via S/PDIF)