Oh god - you bought up the 'a' word. Prepare for a torrent from Pandora :P
As with most things in society, it depends where you draw the lines. Nationalism is defined as devotion or loyalty to your own nation. I am British - I believe in the Union of the four Home Countries, loyalty to the Monarch and to my country. Yes, I'm probably an old Tory at heart, but does that mean that I am jingoistic? No, I don't believe so. Jingoism is extreme nationalism - it is often characterised by an overt foreign policy, for example.
As a student of history, it could be argued that jingoism was particularly prevalent in parts of the British Empire during the 19th Century, however, it must be taken into context. It was during a period of nationalism from other countries, notably Spain, Holland, France, Germany etc.