Thank you very much for answers.
Tonight my whole evening will be dedicated to test everything again!
So, it's clear that if the gps works with the pc serial port it needs max232 to be connected to Arduino.
this is the result of a connection gps-pc:
and it's what I expect from the connection with Arduino
When (with max232 in the middle) I've tried to read data and see them in the monitor the result (tonight I'll post it) was "similar" to the right one (I could recognise some carachter, the lenght of the lines seemed to be correct, ecc..).
I hope that the new software layer (newsoftserial) will give me the good result.
Then next step will be string manipulation"!