I have a ScanGaugeII fitted in each of my cars that given me bonus gauges and a tip computer (I know, the 100HP has one anyway, but other cars of mine have/haven't got one) when everything's running well and will read and clear and OBDII codes.
I'd imagine you'll need either a USB or Bluetooth OBDII plug to actually suck data out of the car (which can be found here amongst many other places) and then transfer it into your laptop.
Of course, that's on most cars, but I'm not really up to speed on Fiats yet...
elm327 lead should give you access to most things. I have one but havent tried it yet as the connector seems a bit small the cheap chinese lead i bought.