Detailed Information

Microsoft Baseline Security Analyzer- Highly recommended tool you download and install from Microsoft. MBSA is a FREE, best practices vulnerability scanner assessment tool for Windows 2000, XP and Server 2003. Once installed, run it to scan your system. Any vulnerabilities found are provided a link with a description where to obtain the patch to correct it.  It also finds security weaknesses beyond missing patches and makes suggestive corrections. Version 2.0 is now the latest.

Program Description: "The Microsoft Baseline Security Analyzer (MBSA) checks computers running Microsoft Windows® Server 2003, Windows XP, or Windows 2000 for common security misconfigurations. You must have administrator privileges for each computer you want to scan. It also scans Internet Explorer browser versions 5, 5.5 and 6 for security misconfigurations.

Note that on computers running Windows XP and using simple file sharing, only local scans can be performed. 

Scanning computers for security updates utilizes Windows Server Update Services. MBSA provides integration for Update Services administrators and is a comprehensive standalone tool for the information technology professional. 

Microsoft Baseline Security Analyzer (MBSA) 2.0 is an easy-to-use tool that helps small and medium businesses determine their security state in accordance with Microsoft security recommendations and offers specific remediation guidance. Improve your security management process by using MBSA to detect common security misconfigurations and missing security updates on your computer systems. Built on the Windows Update Agent and Microsoft Update infrastructure, MBSA ensures consistency with other Microsoft management products including Microsoft Update (MU), Windows Server Update Services (WSUS), Systems Management Server (SMS) and Microsoft Operations Manager (MOM). Used by many leading third party security vendors including Tivoli, Patchlink and Citadel, MBSA on average scans over 3 million computers each week. Join the thousands of users that depend on MBSA for analyzing their security state."

Here are sample screenshots of a security audit:   (click to enlarge)