I installed Windows 8 on my Dell Studio laptop two weeks ago, and I found out that the Synaptics TouchPad driver supplied by Dell does not show the touchpad settings screen in Windows 8. I only use that screen to set the touchpad to disable itself when an external USB mouse is plugged in. Well, I could not do it in Windows 8.
Not until now, I mean.
Looking in the forums (specially http://www.sevenforums.com/hardware-devices/149723-synaptics-touchpad-auto-disable-usb-mouse.html and http://forum.notebookreview.com/sager-clevo/449196-np8662-auto-deactivate-touchpad.html) I saw that the solution is very easy indeed: change a single key in the registry.
For those of you who want the "Disable internal pointing device when external USB pointing device is attached" option in the synaptics control panel, open regedit and go to HKEY_LOCAL_MACHINESOFTWARESynapticsSynTPEnh, right click and select New > DWORD (32-bit) Value and name it "DisableIntPDFeature". Modify it's value to 33 in hexadecimal, or 51 in decimal to enable it to be default on.
Works like a charm