Dell C/Dock or upgrade

[inspiron8200guy]

I am thinking of buying a used C/Dock (not the APR) and buying a PCI (not PCI xpress)graphics card because the C/Dock has PCI slots. Does this sound like a good idea, or should I buy the Mobility Radeon 9000 for my laptop. To get my inspiron to work in the C/Dock, I would have to make the BIOS think it's a C840 or such. Does a PCI graphics card even worth the thought.