It was one year ago today (November 8th, 2006) that my favorite operating system officially released to manufacturing!http://windowsvistablog.com/blogs/windowsvista/archive/2006/11/08/windows-vista-releases-to-manufacturing.aspx
In the first year of Vista's life - we shipped only 16 bulletins, only 14 of which were rated important or higher compared to 20-23 or so for XP SP0 (depending on whether you count the bulletins released in late August 2002 or not). It may not sound all that impressive but contrast the security environment of today to that of Windows back in 2001 . . . I would say there is a LOT more interest and sincere research going into finding security vulnerabilities today and people were especially interested in targeting Vista this year given that it was being touted as our most security operating system to date. Given that we managed to ship fewer bulletins in a time where arguably the threat environment is more extreme - I'd say that's pretty good. Esepcially since our competition seems to be holding steady with their vuln counts or if anything getting worse. :)
Also - it's hard for me to believe that it's been over 6 years now since the launch of Windows XP (http://www.winsupersite.com/showcase/windowsxp_rtm.asp) on August 24th, 2001 . . . man that OS is getting crusty.