Where can I buy dedicated vga for laptop? Is this exists?

Hello and welcome to the forums  
I don't think you can change the VGA

Agree, you probably can't. They only way to find out is to take it apart and look for better cards online, but even then there's no guarantee.

As for external cards, there are no viable solutions. There are a couple companies who have made interfaces, but they suffer performance wise.

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...

thanks.

Sure it's possible.

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...

Oh yes.... it's hard... hehehe
thanks