Open gl was good back in the day but Direct x other than the latest dx10 and 11(I really don't see any diff between the two at the moment.) But there was a huge diff when dx8 and 9 came out.
Currently I'm finding the "DX10.1" type approach funny. But really, not much has changed since DX9 vs DX10 - only a few small things were added. And the "DX10 is faster" - well how can you know when DX10 isnt supported on XP.
And of course, who can forget the blistering speed that was Glide. I miss voodoos.
XP still works 100% for me.. and I hope other people think so too. Maybe if enough people refuse to upgrade their OS, openGL will become an industry standard and Microsoft won`t have such a stranglehold over pc gamers.