I'm a strong believer in desktops as they are just powerhouses. I understand he wants the added benefit of portability, but I think he may be taking it for-granted especially for the specific laptop he wants to buy. And as with most "gaming laptops" the price is rather extreme. I know it's hard to determine the ability of it without taking the processor into account, according to him it's an i7 with 8 gigs of ram.
I offered to order and make him a desktop computer if he likes the one I'm in investing in, which is significantly cheaper by the way and is just about better in all aspects aside from the Intel processor.
So, my question is. He expects this to get good framerate on highly processive and graphic intensive titles such as Battlefield 3, Arma 2, Skyrim, and Crysis 2-3. Is he right to invest and spend the extra money? I believe he's just being impatient and is rushing a bad decision.
Is he right to rush ahead and buy a laptop he believes is capable of gaming?
look at where the 640m lies in the chart (2nd tier, close to top of "Mid-Range Graphics Cards"....."With these GPUs you are able to play modern and demanding games fluently at medium detail settings and HD resolution". Click on it and see if you are (he is) happy with how it plays the various games.
As you rightly point out, you'll get far more everything for less money using a desktop. You can do reasonably high end gaming on a laptop - check out any custom laptop manufacturer. Note the 680m SLI option at the top of the table then ROFL at the price. I have a gtx 485m in a clevo based laptop and am happy with 1080p gaming on that but I do understand its limitations.
go to youtube and search for some gameplays. I did see on youtube people playing Starcraft 2 on high / ultra on the gt 640m, me on the other hand i play Starctaf 2 on low with intel HD graphics from an i3 (i have a laptop aswell). I guess the gt 640 will please your friend
The problem with laptops is taht you get diminishing returns for your money a lot faster than in desktops.
In my opinion, if he is a good friend the best thing you can do is inform him as much as possible (try to do it in a way he wont get too confused ) and let him decide exactly what he needs.
Mesab66 gave you a very good starting point (i always recommend the same one, especially for checking out if specific models have problems with overheating), so id probably check there (means you need to know what exact model he was looking at).
The 640M is a okish gaming card for lower details, and in general a good deal, but having an i7 and 8 gb witha 640M is a bit unbalanced.
If it is for gaming, an i5, 6-8 gb, and a 650M-670M will give better performance than the previous setup.
Desktops is far more eficient in price for performance, but you probably will have to show your friend the contrast so he can see it first hand (like on your pc compare high settings vs medium settings, full HD vs HD, etc).
Personally i own both a laptop and a desktop (both gaming grade) and i like them both about the same for diffrent purpouses.
i also agree that it is unbalanced, having an i7 paired with that.
also, is portability that important to him? i have a friend who was an avid fan of notebooks as well, he listened to me and is now very happy with his desktop.
what i dont like about laptops is the very limited upgrade options. and when it goes outdated, you will have to buy a new one, even the freakin monitor. unlike desktops.
if he really wants a laptop, maybe you can give him a different model, a cheaper one perhaps with decent gpu. a 640m is pretty low (even a 640 for desktop) and most of the time the mobile version is slower than the desktop counterpart.
if he can live with low settings then by all means