Is it possible to upgrade the graphics card on a macbook??

Nope. If I remember correctly the graphics card is integrated into the processor.

No. There really isn't a graphics "card" in the MacBook-the Intel GMA950 is an integrated graphics solution, meaning the graphic chips are part of the overall chipset on the motherboard itself, and is not upgradable.

It's not integrated into the processor.. It's a separate chip on the logic board.. That said, it can't be changed without replacing the whole logic board.

As a general rule, graphics processors on notebooks are not upgradable (integrated or discrete). Some newer high end gaming machines are being built with upgradable graphics solutions, but they're VERY high end sytems and upgrading the graphics on those systems is quite expensive.