Hi Virgin Blue and welcome to CS,
All are good machines but the e-61 single boiler machines can be dialled into temperature with a Scace calibration. Once that is done, they are deadly accurate and the perfect shot machine. My pick of the bunch is the Diadema Perfetta with by far the best usability and build quality.
Another lower cost option is the GEE espresso which is at Silvia cost but far more versatile. See http://coffeesnobs.com.au/YaBB.pl?num=1279089567
Hope that helps..