Dude, screw Alienware. Go to XOTIC PC and build a Sager NP9377-S - my fully tricked out config with a 17.3" 120hz matte LCD (awesome for gaming - an option that few brands offer - Alienware doesn't even have a 120hz refresh screen), 4940MX chip, 32GB of DDR3-1600, 2x240GB Crucial M500 mSATA in RAID0, 2x1TB 7200RPM storage drives, 6x Bluray writer, 2xGTX 880M in SLI, 3 year warranty plus accidental damage including lifetime 24/7 tech here in the US, IC Diamond on the CPU and GPUs... 4700 after cash discount. The same machine with Alienware would have been well over 6k and would have been crippled because Dell has busted fan tables (the fans do not kick in fast enough which causes a thermal shutdown) and Dell just crippled the BIOS on 4810MQ, 4930MX, and 4940MX, removing the overclocking options because instead of using a stronger power supply, they chose to weaken the system.
Seriously. Check it out - the base model which is only $2100 and it has a single GTX 880M - the fastest single mobile graphics GPU around.
http://www.xoticpc.com/sager-np9377s-clevo-p377sma-p-6981.html
If you don't want a laptop, their desktops are epic too -
http://www.xoticpc.com/gamingcomputers.php
Far FAR more affordable than the competition and options ranging from mid range gaming all the way up to ultra high quad SLI with custom watercooling!
Do yourself the biggest favor you can and stay away from Dell (Alienware is owned by Dell). Just call their customer service and try to get information on an order and you'll be turned off for life.
It goes without saying... that Macs, no matter how much people try to plug them as such, are terrible for gaming. Save yourself Bootcamp and compatibility headaches and get a gaming PC.