4670 should be better then 240m not by much to my understanding.
note when you buy laptop graphics you can always get cheated they sell you a lower clocked version or a gddr2 instead of 3 version or hell even use regular ddr.
If nvidia had a make sense naming scheme like ATI, as ATI mobile cards performance is just under their desktop equivalent when picking the top mobile version. While Nvidia naming scheme has nothing to do with their desktop equivalents.
It's laptop graphics so you can't always expect much paired with a laptop cpu.