Williams urged users and companies still running XP SP2 to update immediately, and said there's little risk in doing so. While enterprises may have put off deploying XP SP2 shortly after it launched in 2004 -- in large part because it was a major overhaul of the operating system -- XP SP3 is essentially just a collection of already-released fixes and patches.

"There's no compelling reason to delay the move to SP3," Williams said.

has been beating the same drum, reminding users each month's Patch Tuesday of the looming retirement. In April, the company also made on Windows XP SP2 support, announcing that it would take calls from customers running outdated service packs, such as SP2. Previously, it turned those people away.

from the Microsoft site, or obtained from XP SP2 PCs via the Windows Update service.

Gregg Keizer covers Microsoft, security issues, Apple, Web browsers and general technology breaking news for Computerworld. Follow Gregg on Twitter at or subscribe to . His e-mail address is .