In a blog post describing this month's regularly-scheduled security patch release—which will be a humongous, Mac OS X-style carpet bomb deluge of updates—Microsoft Senior Security Communications Manager Jerry Bryant also warned that this year will see three out-of-date Windows versions slip into retirement. And as these milestones pass, users will want to upgrade to newer Windows versions to ensure they continue receiving security updates.

"Last month I started including important information about Windows versions that are reaching the end of their product lifecycle," Bryant wrote. "Customers using these versions should consider upgrading before support for these products end as, once they do, we will no longer provide security updates."

Soon to retire Windows versions include:

Windows Vista (RTM). The initial shipping version of Windows Vista will no longer be supported starting April 13, 2010. Microsoft recommends that users upgrade to Vista Service Pack 2 (SP2) or to Windows 7.

Windows XP with Service Pack 2. This XP version is no longer supported as of July 13, 2010. Microsoft recommends that users upgrade to Service Pack 3 (SP3) or to Windows 7. (Also of note is Windows Vista with Service Pack 1, which will no longer be supported starting July 13, 2011, and as with Vista RTM, Microsoft recommends that users upgrade to a newer version.)

Windows 2000. The extended support phase for Windows 2000 will retire on July 13, 2010. Customers will need to upgrade to a newer Windows version in order to continue receiving security updates.

Microsoft delivers monthly security patches on the second Tuesday of every month (which is today). As Bryant notes, newer versions of Microsoft products like Windows and Office suffer from fewer overall security vulnerabilities—and fewer critical vulnerabilities—than do older versions. So Microsoft recommends keeping these products up-to-date and, when possible, to upgrade to the newest versions. "The latest versions are less impacted overall due to the improved security protections built in to these products," he added.

Regardless of which Windows or Office versions you're using, however, this month promises to be a punishing one for security updates. Microsoft will fix 26 vulnerabilities across 13 security bulletins, 5 of which will be rated critical. Eleven of the security bulletins affect Windows, while the remaining two affect Office