All support for Windows XP and Office 2003 will end in two years as of this past Sunday. Mainstream support for two other entities ends this week however. Mainstream support for Windows Vista will end on Tuesday 10th April, and for Office 2007, today.

Microsoft divides its support lifecycle into two stages: "Mainstream" and "Extended." In the Mainstream phase, software receives the full range of free security updates, stability improvements, bug fixes, and occasional new features. In the Extended phase, only security updates are freely available, though companies with paid support contracts can receive other fixes.

Windows XP and Office 2003 are currently in Extended support. Once this ends in 2014, they'll cease receiving even security updates, leaving anyone still using that software vulnerable to whatever malware the Internet throws at them.

Windows Vista and Office 2007 will be in Extended support from now until April 2017.

Update: For some reason Office 2007 has now had its Mainstream support extended for another six months, and will enter Extended support in October.