Um, I can't believe someone recommended a mac. FOR GAMING. (I honestly hope it was a joke, although it didn't sound like one) Mac workstations might be able to run some of the games he listed, but laptop? Not a chance in hell.
:/
For great power in a great package, alienware isn't that bad. However, they do run on the expensive side for the power you get. A good chunk of you money will be going into the branding, casing, and advertising. If you are gaming more, and absolutely must have a laptop (desktops would be SO much more powerful for much less), you should have ibuypower.com at the top of you list.
I'd probably get this one:
http://www.ibuypower.com/Store/Batta...aming_Notebook
The mobile 285 is roughly equivalent to the gts 250, which I had. It could run crysis on medium/high. You would need a better processor for supreme commander, which the i7 930 would be great for. Note that this actually uses the desktop chip, as far as I could tell, not the mobile chips in most other laptops.
The price is a little higher, but it's pretty great for a laptop.
Now this one has the mobile 285 in sli:
http://www.ibuypower.com/Store/Batta...aming_Notebook
But the processor is also a mobile one. I am totally unfamiliar with the mobile intel chips, so someone else will have to judge whether the one in this is good enough.
The dual video cards should actually be more than enough to offset the (possibly) wimpy cpu though. But it's 18 inches, which might be a bit too large for a laptop.
A lot boils down to personal preference.