That would be weird, AVWW is a Direct3D application so if you start it 3d-mode should trigger for any and all cards in existence even if there is 0 load on the card. As long as any 3D-App is open and does not request actually have a "no motion, no rendering of the frame" function cards are actually required to run in 3D mode
That said, It is possible that if the driver is VERY badly coded it uses GPU load as definition whether to "ramp up" or not. In which case... that could be a problem.
See attached file, GPU load even with many enemies, never goes beyond 20% and as you can see, the GPU never even breaks out a sweat when playing AVWW... in fact, i was doing soemthing in the background (firefox..youtube, 9 tabs) so yeah ,p
Could you get GPU-Z 0.60 and look in the Sensors tab while playing AVWW ? Does it look like this attachement, or does the 3d-mode not trigger?