Ok you have pci express. I agree with powerslave that the Nvidia 6600gt would be your best bet. right now on newegg.com they are between $115 and $150. For the integrated graphics you would just unistall the drivers, set bios to use the pci graphics instead of onboard, load the drivers for your new card and bingo. Gaming heaven.
PS make usre you buy a pci express video card and NOT A AGP CARD
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