Who has a Legal Obligation to Upgrade Windows XP, Office 2003 and Exchange 2003?
The best source of information covering this requirement comes from NIST, the National Institute for Standards and Technology. They have a set of documents that are the standards for many requirements. There is nothing specific in the NIST guidelines about the end of life for Windows XP, however, the need to provide Flaw Remediation is clear and that is what the X, Office 2003 and Exchange 2003 support requirements fall under.
For example, NIST Special Publication (SP) 800-531 requires the SI-2, Flaw Remediation security control, which includes installing...
Smoke testing is a term used to describe the testing process for servers after patches are applied. 
Estimating an average time for patching servers and PCs can be a bit tricky. It can vary from one month to the next, depending upon the number and complexity of the patches released by your software vendors. You must consider all versions of operating systems and have a complete inventory of all your application software to do this job correctly. Our experience has shown that manual patching of systems takes on average of about 1.5 hours each.
This is a basic cost calculator for you to compute your typical monthly cost for patching your servers, PCs, laptops, tablets and associated application software. It also forms the basis for you to begin calculating your Return on Investment for software patching, or for comparison with alternatives to the manual process of patching operating systems and application software—such as Patch Management as a Service, also known as Vulnerability Management as a Service.