Strongly recommend finding a laptop with NVIDIA graphics.

Made me curious why you won't equally recommend an ATI graphics card?

On the plus side for NVidia: Cuda, Linux
On the downside: The OpenGL drivers don't conform to the OpenGL standard.

Going back 4 years or so, I'd have recommended Nvidia. These days I generally prefer using the ATI drivers for development (but then I've typically been doing OpenGL). The nice thing about ATI is that they implement the OpenGL specs to the letter. Rather than crashing in the driver (which is what Nvidia cards tend to do more often than is fun), ATI actually fails with the correct error code, and so it's easy to diagnose any problems. If your OpenGL code works on ATI, it will typically work on Intel and NVidia cards (although you may find that you've run out of resources on the Intel cards). These days though, you can usually test both Intel and something, on the same machine, so it's possibly becoming less of an issue.

I just tend to buy refurbished laptops directly from dell (they have an 'outlet' part of their site, where they sell laptops at knockdown prices). Since Dell has already taken the price hit, it's pretty easy to sell them a year or two later, without losing a huge amount of money, and then you can buy a new one with the latest GPU/CPU specs.

For that price you might want to find something with an SSD as mentioned.

Always buy a laptop with a HDD, never with an SSD! Not all SSD's are equal, and typically computer vendors will choose the cheapest SSD available, rather than the best. Imho, you get a much better deal by buying an SSD of your choosing (along with a cheap 2.5" HDD caddy), and then perform the upgrade yourself. It can often be cheaper (or about the same price) to do that, and you end up with a nice external hard drive for backups etc.

• AMD Radeon™ HD 7730M 2GB or NVIDIA® GeForce® GT 640M LE?
• can you guys tell me the pros and cons of them?

I never saw you mention anything about graphics programming or whatever, so I'm assuming you just mean programming in general. In that case, yes, it's perfectly fine for programming.

Just think of it like this: If people with that laptop can play even relatively simple Steam games (Not necessarily Skyrim), and those games are made by teams of 3 or 4 people, your game probably isn't going to be the thing to crack its back.

I never saw you mention anything about graphics programming or whatever, so I'm assuming you just mean programming in general. In that case, yes, it's perfectly fine for programming.

Just think of it like this: If people with that laptop can play even relatively simple Steam games (Not necessarily Skyrim), and those games are made by teams of 3 or 4 people, your game probably isn't going to be the thing to crack its back.

"[...] and for gaming."

Ah, didn't see that. Well, in that case, you don't need a whole 8 gigglebits of RAM just to play some games. You need like... 4, generally. What you really need is a good graphics card. Others have mentioned an SSD, and yeah, that'd be nice, but what you absolutely need is a good graphics card, like 4GB of ram (generally), and enough holes in the case to keep it from exploding. If the laptop comes with "Intel HD Graphics," my gut reaction is "Oh dear god no."