You wouldn’t think that killing off an operating system that debuted in the first year of the Bush administration would ruffle too many feathers. But an amazing 29% of computers across the globe are still running Windows XP, according to NetMarketShare. That makes it the world’s second most widely used operating system, just behind Windows 7.

After April 8, Windows XP computers will be more susceptible to malware and viruses beginning, since Microsoft will no longer address major holes in the software. Although antivirus software will continue to fend off some malicious attacks, Microsoft’s security updates provide an essential line of defense.

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For Windows XP users, the best course of action is to bite the bullet and buy a copy of Windows 8. The problem is that most older computers won’t be able to upgrade to Windows 8. Many of those consumers will have to buy a new PC. Microsoft has an upgrade assistant that allows people to determine whether their computers are compatible with the latest version of Windows.

For those who are able to upgrade but aren’t ready to make the jump to the fully redesigned Windows 8, Windows 7 is an option. It’s still on sale, offers a more familiar PC experience and will be supported until 2020.

The Windows XP impact will be felt more by companies than by consumers. Forrester Research estimates that 20% of North American and European corporate computers are still running Windows XP. But that will soon change: Forrester forecasts that only 6% of those companies’ PCs will be running Windows XP by April.

That remaining 6% will predominately be small and medium-sized companies and government agencies, where budget restraints may pose a problem, according to Scott Dowling, a Microsoft software consultant for En Pointe Technologies. The vast majority of large Western businesses have already upgraded to Windows 7 or Windows 8, but small businesses have been slower at catching up.

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In China, however, XP-related problems will likely be much more pronounced. About three-quarters of Chinese PCs are running XP, according to NetMarketShare.

Thousands of ATMs will also potentially be exposed after Microsoft ends Windows XP’s life support. A recent Bloomberg Businessweek story revealed that 95% of ATMs in the US are still running Windows XP, and only about 15% of them will be upgraded before April 8.

ATMs have already proven vulnerable to malware attacks, and without Microsoft around to patch things up, it’s going to be a slow, costly endeavor for ATM companies to get their machines updated or replaced. (It’s worth noting that Microsoft has been warning them of this deadline for years.)

So why is Microsoft killing off Windows XP? The operating system has lasted far longer than Windows versions of the past, and patching the ancient-by-tech-standards OS is exhausting valuable Microsoft resources. Microsoft has pushed back XP’s death date for several years after initially planning to kill it off by 2010.

To soften the blow for its corporate and ATM customers, Microsoft will sell custom support that will allow companies to receive additional security patches. But Dowling have heard reports from customers that the cost of custom support is prohibitive.

For the rest of the world, it’s time to get updating.