i have bought and installed, a Nvidia gtx 560. Now my computer runs on the Intel(R) G45/G43 Express Chipset. my manual says that i should disable it, and it refers to my computers manual, which refers to support.dell.com, where i can't find any help
More aboutdisabling intel express chipset
Just connect your monitor to the new graphics card instead of your motherboard and it will be disabled automatically.
you can try unistalling the intel graphics driver which will disable it