Well I bumped up the shaders to 1620MHz, seems to yield me around 4100-4300PPD. Might still have some more juice left in it, don't really know. Would F@H give me some kind of error if the GPU was unstable?
And I'm pulling 246W with my single-core AMD64 3200+ folding too. Better than I was expecting since I thought this old 8800GTS would be power hungry.