To many it seems patently obvious, but not to all: Windows users who do not run updated anti-malware software are much more likely to be infected with malware.
Microsoft released research this week to prove the point in the most recent version of its Security Intelligence Report. They also highlighted the data in a blog entry from the MMPC (Microsoft Malware Protection Center).
The data in the report is collected from telemetry from the Malicious Software Removal Tool which runs each month with Windows Update. The MSRT collects the information from the Action Center API.