Sounds like heresy to me. I think you probably can keep both, but they won't work together, since DirectX drivers won't allow different drivers to render 3D enviroments. I am guessing you'll have to use the GeForce, and uninstall it to go back to the x1250. I sincerely do not recommend trying to use both catalyst and forceware at the same time. Also, I'm really curious as to why would you want your onboard VGA when you have a discrete one.
Mostly I work with OpenGL Apps. For Ex. I could output video frames on my second display (X1250) and have 3d viewport on the first display (7600) both work independently.
And there are some negligible reason:
- I can test how a 3d implementation will looks like on each card (ATI & Nvidia)
- I can compromise some ATIvsGeForce incompatibility issue such GLSL,Cg or HLSL.
- And I can work happily regardless its nvidia optimized apps or ati optimized apps.
After all X1250 is pretty decent with atleast 8.7 Catalyst