There is a terrific experiment underway at http://test.doit.wisc.edu/ It runs until March 10. Upset with a misleading ZDNet article which asserted Mac OS X could be easily hacked in under 30 minutes, a professor at the University of Wisconsin invited people to hack his Mac mini, which was running Apache and ssh. This is a great experiment. It will, I believe, make it very clear that it is the actions of the person in control of the computer which puts it most at risk. Current versions of most operating systems and most server software are not vulnerable unless improperly configured and/or buggy applications are installed.