I can't answer your question on Ram vs. Graphics card, but I can tell you that I purchased an Asus laptop from Newegg in January and am extremely happy with the purchase. 

These are my specs and the Sims 3 runs fantastic.  I have absolutely no lagging anywhere and the display is crisp.  I run everything on high. 

Intel Core 2 Duo T9400(2.53GHz)
6GB Memory
500GB HDD 7200rpm
NVIDIA GeForce 9800M (512MB)

It sounds like the Asus you are looking at has a better graphics card than mine.