This may help some people.
GeForce 4 ti4200, 128Mb 4xAGP card.
I had awful slow-down with 7.0, and terrible graphics deterioration/degradation with OpenGL switched on. I was using NVidea 56.06 drivers.
Changed video drivers to NVidea 44.03. Now OpenGL is cool, full acceleration and no degrading of image.
Video drivers may be an issue to take care of. Hope this may help some folks.