You are to use Windows Updates that scans your computer for what is missing for a fully patched machine that is secure against venerabilites and zero day threats.
START > CONTROL PANEL > SECURITY CENTER
The average consumer is to have Windows Updates set at AUTOMATIC period. Anyone telling you different is trying to get you to circumvent your own computer security. You are to be at Service Pack 3 and Internet Explorer Version 8 as recommended by Microsoft security bulletins....
Microsoft Security Advisory (977981)
http://www.microsoft.com/technet/security/advisory/977981.mspx
Vulnerability in Internet Explorer Could Allow Remote Code Execution
Published: November 23, 2009 | Updated: November 25, 2009
".....Microsoft is investigating new public reports of a vulnerability in Internet Explorer. This advisory contains information about which versions of Internet Explorer are vulnerable as well as workarounds and mitigations for this issue.
Our investigation so far has shown that Internet Explorer 5.01 Service Pack 4 and Internet Explorer 8 on all supported versions of Microsoft Windows are not affected, and that Internet Explorer 6 Service Pack 1 on Microsoft Windows 2000 Service Pack 4, and Internet Explorer 6 and Internet Explorer 7 on supported editions of Windows XP, Windows Server 2003, Windows Vista, and Windows Server 2008 are affected. ....."
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Microsoft Windows Update
http://windowsupdate.microsoft.com/
The Microsoft Windows Update Consumer site provides critical updates, security fixes, software downloads, and Microsoft Windows Hardware Quality Lab (WHQL) device drivers for your ...
http://windowsupdate.microsoft.com/
RUNNING WINDOWS UPDATES - YOUR COMPUTER IS SCANNED BY THEM FOR MISSING CRITICAL SECURITY PATCHES AND THE LATEST SERVICE PACKS.... IT IS AUTOMATIC BY THEIR SCANNING SERVICE OF YOUR PATICUALR CONFIGURATION.
APPLY ALL IMPORTANT AND CRITICAL UPDATES....
RUN A SECOND SCAN AS ""CUSTOM""
ANY DRIVERS UPDATES AND OTHERS SHIPPED BY SOFTWARE COMPANIES THROUGH AND WITH MICROSOFT WINDOWS UPDATES WILL APPEAR THERE. ALSO .NET FRAMEWORKS AND SERVICE PACKS. THIS IS RECOMMENDED AND SOMETIMES REQUIRESD BY MANY MANY SOFTWARES THAT RUN THEM MORE SECURELY AND STABLE. RECOMMENDED STRONGLY TO INSTALL .NET FRAMEWORKS AND THEIR SERVICE PACKS.
You can use Microsoft Baseline Analyzer to check for missing patches and overhaul security scan of your current configuration. Install it at Microsoft ONLY.
Microsoft Baseline Security Analyzer (MBSA) 2.0 is available
Discusses MBSA 2.0, MBSA 1.2.1, and Microsoft Update. Explains how to obtain complete detection coverage for your systems.
http://support.microsoft.com/kb/895660