How many vulnerabilities are on each platform? Here's a vulnerability analysis podcast covering Microsoft, Apple and LINUX
Thanks to Rodney Buike for sharing his interview with Jeff Jones (Director of Trustworthy Computing @ MSFT) who discussed his extensive research of publically available vulnerability statistics.
Rodney contributes to the very popular Canadian IT Pro team blog - it's an excellent source of information about a wealth of topics including UNIX and Security.
Jeff hosts an interesting CSO blog that's focussed on the needs of Chief Information Security Officers (CISOs) and executives.