Even with everything on low and all of the frills disabled BF3 still did not work properly on my pair of 295s.
Now some of that was down to drivers, some of it was just that the game is quite poorly coded IMO. But the fact remains that it was, even with everything switched off, unplayable.
That is strange, i'd have thought those would give decent frame rates with some of the textures turned down.
I stuck my old 9800gt in my machine lastnight, it seemed to cope ok at first (all settings on low) but then soon became unplayable within a few minutes. Didn't have time to checkout why though....
On another note my laptop has 2gb vram, GT435m. Because it is so underpowered, to get decent fram rates everything must be set to low, and then it uses about 400mb vram, not much point having the other 1600mb....