More than a quarter of the 1646 respondents to a recent PC Advisor poll have indicated that they won't be upgrading to Microsoft's eagerly awaited Service Pack 2 when it arrives next month, citing concerns about compatibilities and support.

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

The service pack will be downloaded automatically onto 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.

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, email 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 could render existing applications inoperable.

However, a substantial minority of respondents to the poll intend to jump in feet first. Some 42.8 percent intend to install the product the minute it is made available.