One thing to remember is that Kepler GPUs (GT640/650/GTX660) can and will be different in laptops.
Case in point; Asus GT650m's use GDDR3 which is usually speculated to perform 5-10% (or more) less than a comparable GT650M chip on GDDR5 memory such as the MacBook pro which uses a GT650M with GDDR5 memory.
On the other hand you get manufacturers that love to mess with the speeds of the chips , memory, and cooling which limits performance due to heat.
Dells and Hp's are notorious for getting hot under load. Sony's use a highly underclocked GT640MLE which is 20% worse than a normal GT640M. Sammy's use standard chips but iirc was reputed to also get a bit warm under load. Lenovos are also excellent; same with asus.
If you get a kelper GPU; remember this. Every single chip is identicle be it a GT640m/650m/GTX660m. All that's different is clock speeds; memory interface; and cooling solutions of which all affects the performance of a laptop.
If its samsung vs dell.. i'd take samsung. Would prefer an Asus or a Lenovo or custome ones like a Clevo / Sager