I had to use Windows 7 today, was so slow compared to my Linux box, Chrome lagged.
Apparently OpenGL is easier to code than DirectX (Going from what Manyak said there, he said it took half the code to open a window and draw a triangle in OpenGL than it does in DX or something?) but from a user perspective, OpenGL is more fluid at lower fps and considering nearly every game hasn't taken full advantage of DX10 or DX11 yet, I doubt there is much of a difference at all, it is sad that devs bought into MS' marketing and made OpenGL and DX what it is today, OpenGL at least was better.
one thing that has hurt OpenGL in the game industry was their lack of a specific game fork for it, 3dfx tried to create one, but we all know what happened with 3dfx
but unlike dx, OpenGL has a lot more uses than just as a game API, and it is multiplatform...
that might not mean anything right now, but there is a lot of technology setting on the horizon, that windows will not run on, well not for at least a few more years..so who knows how this tide will come in the end...