As soon as you have manually installed Service Pack 1 (rel. 04-Feb-2008) and Service Pack 2 (rel. 25-May-2009) your Windows Update will start hanging on "Checking for updates..." and Windows Update will be unable to install the ~ 220 security updates released between May 2009 and Vista's end of support on 11-Apr-2017 until you follow the ... More @Wikipedia
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