It's the mortality of the sickness that you need to look at.
The main cause of death with A-H1N1/09 is viral pneumonia with resulting ARDS (Adult Respiratory Distress Syndrome). Even though treated in a hospital ICU, approximately 50% of ARDS cases result in death. In the French study, the number of ARDS cases was found to be one in every 5000 cases, giving the estimate of ARDS deaths as 1 in 10,000 cases of infection.
The number of deaths from ARDS in seasonal flu cases, based on empirical evidence in France, is calculated to be between 5 and 10 each year out of an average annual number of seasonal flu cases of 6 million infections. Until better counts of cases are available, that gives a rough estimate of the deaths due to ARDS resulting from seasonal influenza of one out of a million infected patients.
The 1 death in 10,000 cases from A-H1N1/09 compared to 1 in 1,000,000 from seasonal flu strains gives the prior mentioned indications of A-H1N1/09 being 100 times more virulent than seasonal flu.