this is just a theoretical question, at this time I can perfectly live with Xv, I don't need VDPAU (yet).

My pc has the following setup:
nforce 980a with activated on-board GPU
1 8800GTS 640
1 9500 GT
1 9800 GT

the reason why is that I sometimes write CUDA 1.0 programs which are computationally intensive, and every extra GPU can help.
At normal usage, the 190.53 turns off all GPUs, except the 8800GTS (display is connected to this one). I am very happy with this feature, because the 8800GTS is watercooled (=silent) and the 9800GT is not (=very noisy). That's the reason why I still use the old G80 as main video card: it's silent, and for nearly all activities, its capacities are sufficient.

but now, I learned about VDPAU, and this makes me a bit confused:
- nforce 980a (VDPAU B)
- 8800GTS (no VDPAU)
- 9500GT (VDPAU A)
- 9800GT (VDPAU A)

I have 2 questions:
- can I still use my G80 as default GPU? ( will the driver wake up any additional video card if I use VDPAU?)
- what is the VDPAU compatibility of my system? (none, A, or B?)