- As far as I can tell, the settings aren't overriden in my control panel. I did have it set up that way at one point, but I deleted the profile, and I can clearly see there is no antialiasiing on the final render image.
- I've tried to get error output from debug runtimes but I can't figure it out. I followed Shawn Hargreaves' guide but I never got any output from those programs. If someone could tell me how to do that for XNA 4.0 I would love to try.
- I was using the latest 301 beta drivers for nvidia, I've now downgraded to the latest official drivers (296.10) with no improvement.
- I'll try to get someone with an ATI card to test and see if they have the problem as well
I am aware of the pixel/texel issue, and I do have a + halfPixel in the shader. If that was the issue I think it'd happen on the reference device as well. Also I don't think its an issue of a small rounding error. I think the difference between the values was something like .6 vs 1.