I just suggest that problems with viruses are much more common (and therefore may cause much wider damages) when you're running Windows os. I dare to say that Linux "market-share", although constantly raising, is not encouraging enough if you want to make yourself "popular" by writing another virus or just want to gain control over infected machines. The level of security that results from default installation settings of the OS is not the most important issue when you are hosting the stock exchange - they surely have their experts - but the enviromnet where the OS is running _is_.