but, if a laptop has a "dedicated card" like my G2S, isn't possible upgrade?
In the manual there is the information that card is pci-express... Then I imaginated that is possible upgrade...
But where are you going to get a new card? No one sells them. You'll have a hard enough time seeking out a replacement card, let alone an upgrade.
Then you have to cross your fingers and hope the new card is the same board layout so your cooler will fit, and uses near the same amount of power, and that your BIOS will aptly recognize the new card, and...