So yeah my friend have a laptop HP Pavilion 15-n070sw, and he asked me to find drivers under W7 x64. I have found it on nvidia page (actually this isn't a problem), but as this machine have 2 other manufacturer cards I am aware of hardware / drivers work.
Should I install both drivers for ATI and nVidia graphic cards? This doesn't make much sense
No. You should only install the NVidia and Intel Drivers from HP's web site. If your friends system was not configured with an AMD graphics card, you should not attempt to install any AMD graphic card drivers.