You think it doesn't sound serious because U.S. medical authorities define SARS so expansively, more or less any respiratory infection of someone who has been in one of the affected countries in Asia. That takes in many cases that are probably not true SARS.
Abroad, to be classified as having SARS, you have to have pneumonia, so that all the cases are far more serious.
At some time soon, we should have a working test. Use of that should clarify the stats.