Upgrading to Service Pack 2 (SP2) will cause problems with about one out of every 10 PC running Windows XP, according to research published Tuesday by a Canadian asset-monitoring service provider.

Ottawa-based AssetMetrix probed over 44,000 Windows XP systems housed in nearly 350 companies to come up with its numbers, matching what it found on the PCs against various lists that Microsoft has posted of programs that have, or may have, compatibility issues with the massive SP2 update.

"On average, 10.3 percent of the Windows XP-based machines will have an issue of some degree with SP2," said Steve O'Halloran, the managing director of AssetMetrix Research Labs. "Or better put, they have the 'opportunity' for an issue to arise."

AssetMetrix used Microsoft-made lists -- including one that identifies applications that have an issue with the now-on-by-default Windows Firewall, and another that names apps known to experience a "loss of functionality" when SP2's installed -- to come up with its figures.

The 10 percent rate didn't come as a shock, said O'Halloran, but a new-found correlation between company size and XP usage did. "Actually, I was assuming [the percentage] would be higher, but I didn't expect to spot a statistical difference between large and small companies."

Business with fewer than 100 XP machines, for instance, can anticipate problems with 11.9 percent of their systems, said O'Halloran, while those with more than 100 XP PCs can figure on issues with just 6.2 percent of their desktops.

Smaller companies will have a tougher time with SP2 for a variety of reasons, including a higher concentration of Windows XP PCs. According to AssetMetrix's data, the smaller the company -- as measured by the number of PCs it operates -- the more likely it's a 100 percent XP shop.

By Gregg Keizer, TechWeb News