+1 for Asus one, I have two of 'em, one is the mentioned one and another based on 2nd gn dual core and gt520M
HD 6490M is just marginally faster than Intel HD 3000 Gfx n not suitable for gaming. GT540 is way better than it and will provide you good game playing experience in 1366X768 resolution.
Regarding build quality, Asus is far far better than Dell's sub 40K offerings. In this range all the Dell laptops have heating issues and poor battery life after 1 year. The Asus one has very good battery backup, more than 4 Hrs for normal use and with HD movies it is more than 3 to 3.25 Hrs. Also the laptop's heat exhaust works like a charm and blows the hot air through the side ventilator very efficiently. So grab the Asus one. I have experience with a lot of brands in case of laptop business like HP, Dell, Lenovo and currently Asus and Asus is the best VFM in my opinion.