you said you had a radeon card?
try this nifty tool from Ray Adams, called ATi Tray Tools, basically its a replacement for CCC and uses less resources and gives more settings then CCC.
However some caution must be taken with it, if you don't know what you are doing with overclocking i suggest u tick the disable overclocking in the setup menu.
Anyways get the tool from here >
http://www.guru3d.com/article/atitraytools/189/Once you have it installed right click the tray icon and under display, click settings.
Then click on/off for both of them, and click apply and check to see whether you can run both in "clone" mode.
If that is successful, turn off the one u want to extend into, click apply
then right click your tray icon again, and this time under display select extended desktop and viola it should keep your primary and add the other as an extended
Goodluck!
Kurtis