Microsoft Security Intelligence Report (SIR) v7
The Microsoft Security Intelligence Report (SIR) is a comprehensive and wide-ranging study of the evolving threat landscape, and addresses such topics as software vulnerability disclosures and exploits, malicious software (malware), and potentially unwanted software.
Volume 7 of the Security Intelligence Report (SIR v7) covers the first half of 2009 (January through June). It includes data derived from more than 450 million computers worldwide, each running Windows. It also draws data from some of the busiest services on the Internet, such as Windows Live Hotmail and Bing.
The research is extensive and we encourage you to download the report.