Well, i have the Alienware Area-51 5500 wich has :
-Intel® Core™ 2 Duo E6600 2.40GHz 4MB Cache 1066MHz FSB
-Alienware® Approved Intel® 975X Motherboard
-2GB DDR2 Performance SDRAM at 667MHz - 2 x 1024MB
-Single Drive Configuration 160GB Serial ATA 3Gb/s 7,200 RPM w/ NCQ & 8MB Cache
-256MB Radeon® X1650XT
-AlienAdrenaline: Video Performance Optimizer
-High Definition 7.1 Audio - Standard

And may i say, its a damn monster. I got all settings high including shadows and the unit scale is in huge. I havent had any lag problems so far, i havent tried a 7000 units in the field though.