No you can not "link" the 8600GT with your onboard HD 3200 video "card".
If you just bought the 8600GT, to correctly install the drivers and avoid complications download Driver Sweeper
along with the newest drivers for the video card, then
proceed with uninstalling the drivers for your current HD 3200 solution.
Reboot to Safe Mode and run Driver Sweeper removing any left over drivers (if any) of your old video setup.
Reboot again, entering BIOS and disable the onboard HD 3200, boot to Windows and install the newest drivers for the 8600GT.