Microsoft shipped its Windows XP operating system to PC manufacturers on Friday, accompanied by much complaining from rival Sun Microsystems.

The "gold" release seals Microsoft's decision to keep Java source-code out of the operating system, said Toni Duboise, an analyst at ARS, a market research firm.

Beta copies of XP and Microsoft's new browser, Internet Explorer 6.0, didn't include the Java virtual machine (JVM) that was used in Windows 2000 and Internet Explorer 5.0.

The decision prompted Sun to launch full-page ads in several national newspapers earlier this month. Those ads urged users to demand that Microsoft and PC vendors such as Compaq and Dell support Java.

Preload controversy "Sun is fully prepared to support customers that Microsoft is abandoning," said Bill Pataky, group product manager for fundamental Java technology at Sun. "Microsoft is making it hard; we're trying to make it easy." Consumers would prefer to have the JVM preloaded rather than download it on demand, he added.

Microsoft officials contended that a copyright infringement lawsuit filed by Sun barred Microsoft from including the JVM in Windows XP. They said it would be available on Microsoft's Web site.

Sun officials countered that Microsoft refused to license the technology without infringing upon Sun's copyrights. Sun pledged to develop a JVM that's compatible with Internet Explorer 6.0. It will be available for free download from Sun's Web site by XP's October 25 ship date, Pataky said.

But JVM won't be available in time for PC makers to include it on their PCs. A spokesman for Compaq said the company will ship its PCs with Microsoft's version of the JVM.

Rob Enderle, an analyst at Giga Information Group, said that stressing the inconvenience of downloading the JVM could backfire for Sun because it could cause developers to shy away from client-side Java development.

"Instead of downplaying the difficulty of downloading the JVM, what Sun is doing is creating this huge exposure on the issue," said Enderle. "At the end of the day, most developers don't want to be in the middle of some battle. They'll use something else."