The first answer you'll get here is whether you're certain you're don't want to just build everything yourself. If not, fair enough, it's not for everyone.
Unless they've changed more recently, Ailenware's customer has apparently been going downhill over the last few years. And I'm not quite seeing what else they're doing to justify the increased cost. You've got a better processor, better harddrives, better warranty, and (theoretically) a better power supply. Unfortunately, there are way too details missing to judge the quality of either system for certain.
If I was limited to those two choices, I think I'd be going for the Dell.
Edit: See, I told you that'd be the first answer