is a 1.3GHz CPU which is probably overclocked in that Alienware.
So you looking at 'better' GPU in the Alienware vs 'better' CPU in the ASUS.
It's a toss up as to which will perform better.
Older games like WoW, Rift, Total War will probably like the better CPU more and not held back by the older GPU. Core 2 Duo P8400 review
Still a tough call.
I'm guessing since the Alienware (probably 2010 model?) had the lower new sell price it's not as old as the Asus (maybe a 2008 model?).
It's going to be your call, but I think the Alienware might have an edge in reliability over time, since it's not as old.
Is your friend going to toss in an external DVD drive for the MX11?