The major changes to Windows XP brought by Service Pack 2 are bound to cause support headaches. Analysts, users, PC makers and Microsoft all expect a spike in help desk calls.

SP2 is due out in the third quarter of this year, so could be available as soon as next month. The service pack will be downloaded automatically into many PCs through Microsoft's Windows Update service and could create problems, including breaking current applications, disrupting networking set-ups, and prompting non-technical users to make PC configuration decisions that may be beyond their grasp.

Meanwhile, Microsoft is still working on a plan to support the security-focused update. "We're working hard on getting together a support plan," says Matt Pilla, a senior product manager at the software maker. One decision has been made: Microsoft will offer no-charge, worldwide telephone support for the service pack, Pilla says.

Microsoft is returning to its policy to provide free support for service packs after leaving support for Windows XP SP1 to the PC makers, Pilla says.

Nevertheless, Hewlett-Packard, Dell, and Gateway are also gearing up for the release of SP2 and will support their customers, spokespeople for the PC makers say.

Although Microsoft has deemed Windows XP SP2 a service pack, the update really is more comparable to a Windows upgrade. SP2 contains bug fixes and updates, but it also offers new features and makes significant changes to the Windows software in four main areas: network protection, memory protection, e-mail security, and browsing security.

In addition, Microsoft has made something of a trade-off with SP2, focusing on security at the expense of compatibility. As a result, SP2 can render existing applications inoperable. Microsoft has urged developers and IT professionals to test the update. A second release candidate, likely the final test version, was made available earlier this month.

The changes combined with the automatic update are especially worrying to Thomas Smith, manager of desktop engineering at a large Houston-based company. During testing of the service pack he found that the about 5000 Windows XP desktops he manages will no longer be able to connect to the home office with the update installed.

"It will break our enterprise to a point," he says. The PCs use the Internet and VPN software from Cisco Systems to connect. What's more, because SP2 switches on the Windows Firewall by default, Smith's remote management tool supplied by Altiris can't connect to the PCs to correct the problem, he says.

"We will have lost contact to our end-users through Altiris because the ports will be locked," Smith says. "With the firewall being flipped on, our ability to fix any problems without having end users call the help desk is gone and help desk is money," he says.

While Smith's problems might be isolated, SP2 makes changes to Windows that all users will notice. For example, the Windows Security Center will alert a user if their system is not sufficiently secured. Also, a security wizard pops up after installing the update asking a user to make decisions about settings such as automatic updating. Another new feature is a setup tool for wireless networks.

Consequently, all users may have reasons to grab the phone and call support. "The first time Windows Security Center pops up and says your computer is not secure, that can lead to a panic attack," says Joe Wilcox, a senior analyst at Jupiter Research. "Or what if a warning you've never seen before appears when downloading a Web page?"

Microsoft recognises that there will be an increase in support demand. "I definitely think we will see ramped up support requests," Microsoft's Pilla says. "What we have here is a security-focused service pack release that is going to have some significant impact on people's systems."

But Microsoft doesn't yet know how it will deliver support. It could establish a dedicated, toll-free support line, Wilcox suggests. In the USA and Canada the (866) PCSAFETY support line it has for issues related to computer viruses could be extended to cover SP2, he says.

With security being one of Microsoft's top priorities, the company has set aside marketing dollars and is planning campaigns online and with PC makers to get users to update their systems, says Rich Kaplan, a corporate vice president in Microsoft's Security Business & Technology Unit.

"The benefit of getting people to SP2 outweighs any increased support burden," Kaplan says. He emphasises the urgency for IT professionals and developers to download and test SP2 and report any issues to Microsoft.

Directions on Microsoft's Helm agrees. "This is the right thing to do," Helm says. "Users continue to be whacked by worms."