Ok, I have created a sound.conf file in /etc/modprobe.d like this:
options snd_hda_intel index=0
options snd_hda_intel index=1
and now my audio is working on movies, mp3 and flash (Youtube etc.) and this is my actual /proc/asound/cards:
0 [VT82xx ]: HDA-Intel - HDA VIA VT82xx
HDA VIA VT82xx at 0xfbffc000 irq 17
1 [NVidia ]: HDA-Intel - HDA NVidia
HDA NVidia at 0xfbbfc000 irq 25
Finally the damned HDA Nvidia is no more the default one...
Now I still have just one problem: the microphone over skype. I have another machine with the same OS but with just one audio card detected and Skype and microphone are working perfectly. The Alsa levels are all at maximum level and correctly stored, what could be the problem?
Thank you so much to all for help