Hmm...and yet, the link says that a) the graphics have an upper limit based on the chip & OS (in his case, the i3-3110M has HD 4000 graphics, which top out at 1GB maximum for Windows XP & 1.7GB for Windows 7), and b) the graphics can also be set to a fixed amount by the motherboard/laptop manufacturer.
It sounds like in this case he's on a fixed amount of VRAM, so adding more to the laptop will speed up the laptop but not increase the amount available for VRAM.