I followed the steps of this guide. I've installed the drivers without any problems with sudo dpkg -i fglrx*.deb.

The next step is Generate a new /etc/X11/xorg.conf file, but I can't do this due to the following reason:

When I enter sudo aticonfig --initial -f the terminal show me this output:

sudo: aticonfig: command not found

This problem is caused by an error with the symbolics links into the fglrx directory. Look at this section, where you can see -how to fix it- but it doesn't work for me. Why it doesn't? Because after I enter sudo update-alternatives --auto gl_conf the terminal show me this:

update-alternatives: error: no alternatives for gl_conf.

What I have to do to fix this problem? GC: ATI RadeonHD 6670