Yes, the memory on the video card is not at all affected by the memory on the motherboard, so it will work fine as long as you have the appropriate slot on the motherboard.
Whoops didnt realize it was a laptop, in that case you are stuck with what you have, there are a few laptops that allow GPU upgrades but the upgrades are very expensive.
So, what exactly is the difference between a ddr2 and ddr3 video card operations? What does the number mean and how does it benefit me by going from a 2 to a 3? I have a ddr2 vid card right now but will most likely be upgrading to a ddr3 card this xmas.