Which laptop to choose? Lenovo IdeaPad G780 vs Asus X75VC-TY

Hello,
I've been looking for a laptop in the rage of 600$ and my searches narrowed down to these two options:

Lenovo IdeaPad G780 17.3"
CPU: Ivy Bridge 2020M@2.4 GHz
RAM: 4GB DDR3@1600 MHz, upgradeable to 8GB
HDD: 500GB @ 5400 RPM SATA II
GPU: nVIDIA GeForce GT 635M 2GB
PRICE: 634$
http://www.oktal.ro/laptop/lenovo-ideapad+g780+ivy+bridge+2020m+4gb+500b+nvidia+geforce+gt+635m+2gb+freedos+dark+brown-o93651.html

and

Asus X75VC-TY010D 17.3"
CPU: Sandy Bridge i3-2370M@2.4 GHz
RAM: 4GB DDR3@1333 MHz, upgradeable to 8GB
HDD: 500GB @ 5400 RPM SATA II
GPU: nVIDIA GeForce GT 720M 2 GB
PRICE: 625$
http://www.oktal.ro/laptop/asus-x75vc-ty010d+i3-2370m+4gb+500gb+nvidia+gt+720m+2gb+freedos-o94095.html

The Lenovo has a weaker CPU but a better GPU and the Asus has a better CPU but a weaker GPU, at least as far as I can tell by all the research I did.

The laptop will be mostly used by my gf for internet browsing, watching (hd) movies, excel work and other regular girly usage, but I will occasionally use it for playing games like Skyrim, Hitman Absolution, GTA 4, Grid 2, Arma 3, Assassins Creed 3, etc. Now, I'm not interested in playing those kind of games on high settings, low or medium will suffice.
Battery time is not important since it will be used mostly at home. I'm much more interested in the overall quality of the product, since we'll be using it for at least 4-5 years and I kind of want it to be a durable efficient machine.

Which one would fit my needs better?
Are there any other 17.3" options I should look at in the 600$ (500euro) price range?
As far as I know, Asus products are of a better quality when compared to Acer (not sure about Lenovo) and this is the reason I prefer a lower spec but a better quality.

Thank you!