rotated grid AA
 

Using the 52.16/53.03 Forceware's, which multisampling FSAA modes use a
rotated grid pattern and which use ordered grid? Are there any hidden
modes (RivaTuner, registry, etc) that use a different grid mode at the
same sampling (i.e. a different 4x, different 2x, etc)?

Using the 52.16/53.03 Forceware's, which multisampling FSAA modes use a
rotated grid pattern

Only AA modes using multisample 2x modes use rotated grid, and if it is a
combined multisample/supersample mode, the rotation only applies to the
multisample half.

Anyway, you don't really want to use the mixed modes, since they're SO much
slower than plain multisample.

Are there any hidden
modes (RivaTuner, registry, etc) that use a different grid mode at the
same sampling (i.e. a different 4x, different 2x, etc)?

No current Nvidia chip has programmable sample patterns, so the answer is
no. There's a bunch of weird combinations of ms/ss, but they all use the
same basic sample patterns, which are rotated 2x/square 4x ms and
rectangle/square-only ss.