Diags included swapping another nVidia card (TNT AGP) for this one.
Both cards ran flawlessly on eachother's systems.
Then the drivers were updated to beta 40.41.
This brought things to close, but not perfect.
The sound card came unseated.
Things seemed to be better, but still some tearing.
I reset the bios to "optimal" from my custom settings.
I swapped the SB Live! for an ESS Solo 1.
(older, no positional audio acceleration)
Everything wrks like a champ.