Computers running Windows XP will be vulnerable to hackers after April 8

The deadline for installing secure operating systems on federal government computers will pass next month with the job incomplete, leaving hundreds of thousands of machines running outdated software and unusually vulnerable to hackers.

Federal officials have known for more than six years that Microsoft will withdraw its free support for Windows XP on April 8, 2014. Despite a recent rush to complete upgrades, an estimated 10 percent of government computers — out of several million — will still be running the operating system on that date, company officials said.