Mobile Workstation

I currently have an NVIDIA Quadro FX 1600M graphics card?
I want a better one…it has to be an NIVIDIA Quadro though…what card do i get and what (other then buying the better card) do i need to do?
Its for my laptop HP Compaq 8710w Mobile Workstation which i got free but the original OS was Vista and its now XP(i didnt change it…thats how i got it)
You usually cant change graphics chip on laptops.
HP Elitebook 8440W Mobile Workstation Notebook Review – HotHardware