I guess it also depends on what shaders you want to use. SEUS is well known for being really hard on your PC, while some lagless shaders can be run on a laptop.
A GTX 750 would be just enough to run some shaders, but I agree that a 950 would be a lot better. Don't forget to look at AMD as well, although their GPUs usually use more power, and their customersupport isn't as good as Nvidias, they're pretty much the way to go if you want the best performance per dollar.