One reason is that new tools such as Windows Update allow Microsoft to dribble out smaller fixes to its new OS whenever necessary.

A senior Microsoft official said the company doesn't plan to issue a major service pack for Windows Vista because the operating system is "high quality right out of the gate." Another reason is that new tools such as Windows Update allow Microsoft to dribble out smaller fixes to its new OS whenever necessary.

"Will we continue to have service packs? Yes we will," said Michael Sievert, corporate VP for Windows marketing at Microsoft. "But they have a different level of importance today as people get their updates in real-time using Windows Update," said Sievert, according to a transcript of a conference call he held Monday with financial analysts.

As a result, Sievert said Microsoft won't release a "big bang" service pack for Windows Vista similar in size and scope to Windows XP Service Pack 1, which was issued in 2002 with mixed results. That 30-Mbyte download was designed to patch major security holes, improve Windows XP's overall performance, and help Microsoft comply with U.S. Department of Justice mandates.

Sievert said new development tools and processes that Microsoft employed during the creation of Windows Vista also lessen the need for a major service pack. Among other things, the company used automated reporting technology that allowed it to collect bug reports from beta testers in real time, "and then code against those as we were developing the operating system," Sievert said.

Corporate IT managers and home users alike may welcome the fact that Microsoft doesn't plan to drop a major, monolithic update to Windows Vista, the consumer version of which launched in January. After the release of Windows XP SP1, thousands of Microsoft customers reported that the revisions caused their computers to run slowly or crash altogether.

Sievert didn't say when the planned service pack-lite for Windows Vista would be released. "We haven't established a time line," he said.