Hi Carlo – What is your native language? If Italian then I think your best bet is use the Italian version you have so the User Interface will be in Italian.
Microsoft Office 2003 Italian Language Pack
Microsoft Office 2003 Language Interface Pack
Italian Office 2010 includes the following language proofing tools I believe:Italian, English, French, German. So you can avail of the French dictionary using the Italian Office 2010. As an aside French Office 2010 contains the following companion proofing tools:French, English, German, Dutch, Arabic, Spanish. More info on changing proofing language for Office 2010 @ Hope this helps!