Simple. Before this becomes a flame war, go here:

http://nexe.gamedev.net/General/D3D%20vs%20OGL.asp

Now, if you like the first or third one, go to nehe.gamedev.net and take those tutorials and/or buy the book "OpenGL Game Programming."

If its the second, nexe.gamedev.net should have some tutorials. I hear the book "Beginning Direct3D Game Programming" is good.

Good Luck.

Try to make your decision fast before people start flaming you over this topic . The real decision is really personal preference, unless of course, you work for a company that uses Direct3D or OpenGL. With Direct3D being on version 8, and OpenGL being on version 1.3, they are largely the same. The gap is closing between the two. there seem to be more books out on Direct3D, but IMHO, the few OpenGL books are very good. but you don''t even have to spend money either! hop on over to nehe.gamedev.net, the best OpenGL tutorials on the web. If it''s Direct3D you want, theres plenty of sites, one,nexe.gamedev.net, is a reproduction of NeHe, except for Direct3D. Theres a lot of sites on both API''s. Go through all of Gamedev.net''s hosted sites and check out some of there tutorials. or just search for OpenGL+tutorials, or Direct3D8+tutorials on the web. Also, if youve programmed DirectX before (preferably DirectDraw), it''s easier to get what I call the MicroCOM programming, which is how you program Direct3D(create instance,initialize,create other instances, initialize them, call Couple-o''-Functions()) if youre kinda losing me, thats ok, just go to the tutorials or buy a book on the subject and you should be pretty well off.

I chose OpenGL, because it has the reputation of being more portable to console hardware. The downside is that OpenGL does graphics only, you have to use something else for input, sound, and the rest.