All the answers on how to figure out which you have are correct. In 2000 Kawasaki made both a Fi and a carb version of the Classic. Some things, many in fact are interchangeable between the two bikes, but not everything. Fuel tank and instrument panels are different as are the seats and a number of engine components. Also you'll find that specific intake parts will NOT interchange between the 2000 Fi an post 2004 versions as they used completely different throttle bodies and Fi controllers.
In either case, carb or Fi you've got yourself one fine motorcycle.