After two stays, Microsoft will drop all support for Windows 98, 98 SE, and Millennium after Tuesday.

Microsoft has reminded users several times that all support -- including delivery of critical security updates -- will cease after the regularly scheduled July 11 patch date for the operating systems, and has recommend users upgrade to Windows XP.

Previously, Microsoft had extended the final support stage for Windows 98 and Millennium from January 2004 to June 30, 2006; in January, the Redmond, Wash. developer announced it was moving the end date to July 11 to account for one final security bulletin release.

Last month, however, Microsoft announced that it would not update either OS to fix a critical vulnerability first disclosed in April, saying that it was "not feasible" to do a repair.

The next version of Windows to be retired will be Windows XP SP1, which will be put out to pasture October 10, 2006, also a scheduled security patch date. Microsoft's policy is to support a Service Pack (SP) for 12-24 months after the release of its successor. The longer support period, Microsoft states on its Web site, is for "those service packs where [we] believe customers will need additional time for testing and deployment."

Windows XP SP2, the last update and a major refresh of the operating system's security features, debuted in August 2004.

At that time, Microsoft issued tools which let enterprises delay the automatic deployment of SP2 to give them more time for internal testing.