Where are people getting this idea of a tribe called "Itali"? Maybe I'm just missing something, but it doesn't ring any bells for me... do you just mean the heterogenous group of people sometimes termed in Greek Italoi, including the many different groups of Samnites, e.g. the Pentri, Caraceni, Caudini, Hirpini, and later the Frentani... then there are the Brutii and the Messapii... Umbrians and Sabines and Faliscans further north. The Etruscans the Greeks referred to as Tyrrhenoi. All of the peoples save the Etruscans and possibly the Messapii spoke languages related to Latin (they all being part of the Italic language family of Indo-European), and probably shared genetic ties as well (although you can never be sure based solely on linguistic evidence).
Viteliu is the Oscan (language of the Samnites) word for calf, related to the Latin word vitellius. You can see it used on a coin issued by the revolting Socii during the Social Wars, as part of an attempt to create/regain an identity distinct from that of Rome. http://www.sas.ac.uk/icls/imaginesit/sampl.../italia001.html
In fact, there's a whole site dedicated to native languages of Italy titled "Viteliu":
http://www.evolpub.com/LCA/VTLhome.html
Some points in reference to the thread Viggen noted:
It's risky to trust ancient authors too too much when they're talking about the movements of peoples.
The Romans would have distinguished between Greeks and Italic peoples, and between the Italic peoples themselves.