Sun Microsystems may have missed its opportunity to get the newest version of Java on PCs loaded with Microsoft's new Windows XP operating system. The company acknowledged that because of timing issues, no PC maker has opted to incorporate Sun's version of the Java Virtual Machine -- or JVM -- in Windows XP systems. Case in point: Compaq Computer has stated that it will incorporate Microsoft's JVM in its upcoming Windows XP PCs. Compaq's decision to go with Microsoft, especially if followed by other PC makers, will likely thwart Sun in its attempt to show what can be accomplished with the Java programming language. Java programs have been increasing in popularity on the Web. Sun's JVM, a piece of software that lets computers run Java programs, is designed to show Java applications off in the best possible light. By contrast, Microsoft's JVM is based on four-year-old technology. Sun has been writing code furiously since Microsoft's April decision not to ship the JVM with Internet Explorer 6, which is integrated into Windows XP. Sun had planned to offer an IE 6-compatible version of the JVM but won't have it ready in time to ship on new Windows XP PCs. While initially viewed as a blow to Java, Microsoft's JVM pullback also presented Sun with a unique opportunity to deliver a faster, more feature-laden copy of the software to consumers. Because of a legal spat and eventual settlement between Sun and Microsoft, the Redmond, Wash.-based software giant distributes the 4-year-old version of the JVM. "This would be a good opportunity for Sun to get out a newer version of the Java Virtual Machine that delivered a better customer experience," said Technology Business Research analyst Bob Sutherland. But some PC makers said they simply can't wait for Sun to deliver an IE 6-compatible JVM. Naila Seif, director of software marketing for Compaq's Access Business Group, said the company on Friday finalized its decision to ship Microsoft's version of the JVM with Windows XP systems. "We have offered every (PC maker) the opportunity to ship our Java VM if they wish," said Jim Cullinan, Microsoft's Windows XP lead product manager. "They also can ship any other Java VM." Sun did approach Compaq, "but very late... late last week," Seif said. "My main interest is to ship Windows XP in a timely fashion and provide customers with the best experience. Sun is very interested in having a dialogue with us, but we're not going to put any risk to our schedule." Sun spokesman David Harrah acknowledged, "That's essentially what I'm understanding too -- that essentially (PC makers) have to have their code basically set up and ready to go like now." Windows XP will formally launch on Oct. 25, but Microsoft is giving PC makers a head start selling the new operating system. Windows XP systems are unofficially scheduled to go on sale Sept. 24, making it difficult for Sun to get its JVM to PC makers in time to meet the date. Microsoft is expected to release final--or gold--Windows XP code to computer manufacturers within the next few days. "What I'm hearing is there are a number of companies interested in shipping (the JVM), but the first round of machines and support will probably have Microsoft's JVM in it," Harrah said. Sun's problem is that the current version of its JVM, 1.3.1, will not work with Internet Explorer 6. Windows XP runs 1.3.1, but because Microsoft abandoned the Netscape-style plug-ins in Internet Explorer 6, the browser can use only Microsoft's JVM. Sun says Java is appealing because of its ability to run programs identically on many different computer systems -- such as those using Apple's Mac OS or Microsoft's Windows -- without having to rewrite the programs for each OS. But to run the programs, typically in a browser, the PC must have a copy of the JVM. Although Sun is developing a compatible JVM, there wasn't enough time to get it ready after Microsoft's decision became public at the end of July. Harrah couldn't promise quick delivery of the software, either. "What we're saying right now is when XP ships formally (in October), we will have a JVM available for download," he said. "Hopefully, we will see other people distributing it as well. We're certainly working hard to have it sooner." Still, Sun isn't out of the running yet. "Yes, we're going to ship a JVM, but we haven't decided which flavor yet," said Tom Kehoe, spokesman for PC leader Dell Computer. Sources close to Gateway said the PC maker had not reached a final decision on the JVM but would likely not ship one with Windows XP PCs. The reason: Downloading the JVM is considered convenient and fast enough for the majority of customers to acquire it that way. But Compaq didn't see it this way. Internet Explorer 6 users are prompted to download the JVM the first time they go to a Web site requiring Java support. But that file, while easy to fetch, is a 5MB download, big enough to pose a challenge for those with dial-up Internet access. "Even though it's available for download on the Web, we realize quite a few people working at home or in small businesses are using a 56kbps modem," Seif said. "We decided to install it so they have all the tools they need to have a good experience with Windows XP." While PC makers grapple with how best to serve customer needs, behind the scenes, Microsoft and Sun continue to exchange blows over the JVM decision. In adverts appearing on 11 August in three major newspapers, Sun asked consumers "to demand that Microsoft include the Java platform in their XP operating system." Last week, Microsoft responded with an open letter to Sun. "Sun works hard to create an image of itself as a leader in openness and choice with Java," the letter states. 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