There is an extremely knowledgeable English attorney who practices law in Rome who has posted frequently on the now defunct Italy Mag forums and can advise on taxation issues for expats. If you are serious about moving to Italy it may be well worth it to contact her. She was always generous and forthcoming with her adivce on the forum. I am not able to post the URL but you can Google her law firm also.

Her info is:

Charlotte Oliver
Studio Paoletti