[gerbilcannon]

About directx 8.1, you very likely won't notice any performance difference with it, and the majority of users likely don't have any problems. A few users will notice some small bug fixes (and some major bug fixes if you're using a Turtle Beach Santa Cruz sound card) but overall, it isn't worth the upgrade and the final should be released very soon.

 

[gerbilcannon]

Driver version/tweaks/other extraneous stuff can make a pretty big difference in the opengl vs. d3d performance. But on the average system running an nvidia card, opengl will have the better performance. Opengl also has a slight advantage in display quality as it supports subtractive blending on certain cards.