Official version is the downloaded *.bz2 file from blender.org, right? So, I extrect it, and just run the executable file. It´s enough? I don´t need to install the blender version from Software Center first?
Yes, that is the official build.
As I mentioned in a link that I had given you, for the official version from tar.bz2 can work, you need first to install some dependencies. The easiest way to do that is to install blender from the software center, where those dependencies are installed automatically. Once you do that, you can now uninstall blender from the ubuntu software center (dependencies remain installed - I hope), and you can use the official version from tar.bz2 now.
Using Blender from tar.bz2, perhaps you need to associate .blend extension to be opened with the executable “blender” where you have copy the extracted folder from the tar.bz2. Again, I know how to do that in KDE, but not in Ubuntu.
Ah, ok! Now things became clear! 
So, I´ll do that.
Thank you very much, for your, and other users patiance.
Hi guys!
Everything is working! Thanks. After installing the nVidia driver from Software and Updates, the marked edges disappeared and CUDA is available.
I have installed Blender from software center and downloaded the newer version (2.70). I extract the file in Desktop and it’s working. I decided to keep old version of Blender, because I don’t know if the dependencies, that YAFU told about, will be keeping or not.
Thnaks again