Well, Lag isn't just because of a slow computer. Remember my Alienware? Yeah. Can't walk through Abassa. Why? Bad Internet. SO, if you have bad Internet, then you will most likely still have lag. Not as bad though.
Anywho, hurry up and order it! >:O Alienware took two weeks to get my computer to me, so the sooner the better. However, you might have better luck, since mine is a 30lb desktop. Mine is much older, but to tell you something about Alienware's performance, it can still hold up to the modern day computers. I've actually gotten PMs back in my CSS days about how many Ghz my comp was, that theirs was 3.0. I told them "2.6". They laughed at me, but I had no lag. :P
Anywho, we hope for you to get back soon!