I'm having the same problem. I'm using an HP Compaq NX9005 laptop which has a Radeon IGP 320M graphics card. I want to use my 15" TFT monitor as the primary and the laptop monitor as secondary.
I upgraded the drivers for my graphics card and since then I've had the problem (I remember having more advanced options in the Display/Settings/Advanced window and they are no longer there. I've tried rolling back to the previous drivers and installing alternatives but to no avail.
I've also recently installed Windows XP SP2.
I'm currently running version 6.14.10.6368
Any help would be gratefully appreciated