I'm sorry for the question...
I would like to try the option Copy dvd to nero digital option present in nero recode2, to see how works the mpeg4 nero digital, but when I click on the appropriate menu appears this message:
Due to patent license restrictions, Dolby Digital 5.1-channel decoding is not available. This feature can be added by installing the multi-channel plugin.

After closing this message windows appear another (DVD-Video plug-in required)
similar, asking for aDVD-Video plugin and showing some links to find inf or purchase..

Have I missing something?
I usually watch dvds and divx and have ac3 decoder installed

Have you installed Nerovision? Sometimes you need to enter your registration key again seperately there, don't ask me why.

Sure you have the registered version?

So, now I solved, needed to enter again the reg key in Nerovision, as said Garf.
Thank you for the answers.
I'll try the program.