GT 540M would probably run D3 'OK'. Running on Medium graphics on a 1600x900 or 1920x1080 resolution screen? Might be a challenge. We don't know that much about D3 yet to be certain how it would perform. Remember, a laptop GT 540M video card is about equal with a desktop GT 430 graphics card.
Whats the 'larger than 15" screen really mean? You want a BIG screen, or you want higher resolution than 1366x768, like 1600x900 or 1920x1080? You can get that in a 15" laptop so it's still portable, but has a nice working/gaming resolution.
The GTX 560M graphics card Mazir suggested is about equal to a desktop GTS 450 which is about where you can be certain D3 would run strongly. GTX 460M or Radeon HD 6870M would also be a good choices. ASUS G73SW-XT1 $1200 Core i7-2630QM & GTX 460M.
If you're going Mac's route,then forget about gaming.Those who get Macs and install windows for games,have wasted their money IMO.
If GTX 560M is too much for you,then consider a laptop with GT 540M/555M such as ASUS N53/N73 or XPS 15
i need a durable laptop that also looks good. not really what you can expect from a 600 dollars budget laptop.
That's a 'want' and not a 'need'.
I can't really place the thin & light models in the durable laptop category.
3 biggest threats to longevity (your 3yr goal) are accidents, theft and malfunctions.
You might want to look over the business class models which have that extra bit of ruggedness and durability designed and built in. They also tend not to be such a 'theft magnet'.
And depending on the model, you can get a wider range of options than you can in the Series 9 - like a 1600x900 resolution screen and Blu-Ray player.
A good example: Dell Latitude E6420 Review as a bonus it's looks 'don't suck'.
Another: Apple MacBook Pro 13-inch (2011) Review
I'm curious, why between Samsung and VAIO. All VAIOs I've seen have a combination of mediocre reviews and terrible price/performance.
As for my recommendation, if you want a sexy laptop I guess that is kind of Macbook Air territory, and most people I know that have owned a Macbook product have always loved it. If you want more price/performance that looks pretty good get like a rebranded Clevo (Sager) or a ASUS/Acer with a NVidia 560M.