With Microsoft now saying that the next major service pack for Windows XP will not ship until 2008, some Windows users are wondering whether the software upgrade will ever be released.

"The fear is that Service Pack 3 will just get killed off," said Jeff Centimano, an IT consultant with Levi, Ray & Shoup. The concerns stem from Microsoft's announcement of "preliminary" plans to ship SP3 in the first half of 2008, later than previously expected.

That puts the update within months of the early 2009 cut-off date for mainstream support for the XP OS (operating system), and users are now concerned that Microsoft may not feel that a Service Pack 3 is worth the effort.

"That's exactly how it worked out for Windows 2000," Centimano said.

In late 2004, Microsoft scrapped a planned Service Pack 5 for Windows 2000 Server, electing to instead release an "update rollup" of security-related patches for the OS.

Windows XP administrators say dropping Service Pack 3 would make their lives harder. "A service pack has been quality assurance tested with all of the hot fixes together as one installation package," said Ethan Allen, a quality assurance analyst. "If you were to take 500 hot fixes and install them one by one, eventually you might run into problems because they weren't all quality assurance tested as one package."

Microsoft bills these rollup releases as easier to install, but they don't include as many features as a full service pack, users say.

Directions on Microsoft Analyst Michael Cherry agreed that Microsoft may very well decide to drop XP Service Pack 3. "It absolutely could happen. Microsoft is under no obligation to produce any service packs, ever," he said. "It feels that because these fixes are available through the auto-update, there's less need to create a service pack."

Now that Microsoft has mastered the art of releasing its security patches in a predictable, monthly cycle, it should consider releasing service packs on a regular basis, Cherry believes – once a year, perhaps.

"The thing that I don't understand," he said, "is that on one hand Microsoft seems to promote the concept that customers want predictable release cycles for OSes, yet Microsoft also seems to say that customers don't care how random the release of a service pack is."

Others see a financial motive behind the delay. "Microsoft is going to let users kind of sit there without anything new on XP for a while, because it wants you to move to Vista," Allen said.

Allen, who published an early release of Service Pack 3 on his website last year, believes Microsoft will ultimately release the software. But he said that the planned four-year gap between XP SP2 and SP3 is too long.

"Microsoft is trying to focus more on trying to make a bunch of money than on providing users with fixes for their system," he said.