When you perform the last step, init 5 the X server starts with the new settings. Yous should be seeing the Login screen soon; if not, there was something wrong.

I forgot to mention the most important part, that is to backup your present xorg.conf in /etc/X11/ so that you can replace the newly produced with the old one in the case that the above instructions do not work.

Actually, now that I see your glxinfo output, there seems to be 3D enabled! The Direct Rendering = Yes says so. Maybe you are not satisfied with the performance of your graphics card?