Graphics libraries.

[Andru]

Chesso
For Delphi you must point only to lib/zlib/delphi and souce code of ZenGL. And as I said before - better compile dll and use it instead of separate units.
PS: but maybe you choose wrong place to point paths. Open one of demos and look where I set paths for Delphi 2010

Most Computers now from common companies such as HP and Acer come with the additional drivers.

In 2009 I bought my HP laptop, and guess what? There was no official drivers for Radeon HD 4650 inside(installed, I mean), so my system didn't support OpenGL and DxVA for video decoding using videocard.

WILL
You think so because you are programmer, a lot of people uses computers without understanding whole "system stuff", and because of that publishers prefer Direct3D. And if your game is not something very incredible, you will loose a lot of costumers because of OpenGL. But all this is related to casual/small games.