Sarah Montague interviews Sali Berisha, Prime Minister of Albania. Last week Albania was invited to join NATO. The Albanian Prime Minister described it as the greatest political event of the past two decades. He says in that time the country has gone from 'bunkers, barbed wire and countless concentration camps to a country of democracy and a free market economy'. But it still has a huge problem with corruption and hasn't yet had an election that has been judged free and fair.