Can you shut off an integrated graphics card on a motherboard and replace it with a PCI graphics card? If so, are there brands that perform better with this process than others?
The best PCI video card you can buy is a GeForce 5200 and ordered online it should be relatively cheap. Its not an amazing card but it will make most games playable.
I have run into a few PCs where you can't disable onboard GFX. However, they are usally ones that disable automatically when you install an AGP card(obviously, they also have an AGP slot)