Alienware is overpriced shit. Don't get a laptop for gaming. You will get like double the power out of a desktop pc for the same money.
Agreed. Plus if something breaks on your desktop its not such a pain in the ass to fix it yourself, and parts are more standardized (more 3rd party parts)
just build your own desktop for under a grand that has 3x the power of the laptop for 1/4th the price.
I wouldn't bother with SLI. I've got a 17" Alienware with an i7 and love it. If you look on ebay there's a decked out 17" going for like $500 off and it looks brand new.