The default background for Microsoft 's Windows XP operating system—a perfect blue sky full of cotton-candy clouds above rolling hills with impeccably trimmed grass and daffodils—is the spring day we wish could last forever.

And fittingly, many people wish the operating system would last just as long. Introduced in 2001, Windows XP became so successful that Microsoft extended its support for an industry record of 12 years. Yet come April 8, XP's sunny day is over.

At that time, Microsoft will cut off all user support and halt security updates, leaving the software vulnerable to newly discovered attacks. XP computers will still work, but the "Bliss" background image will just be a facade. The operating system will no longer be a safe place to work or play.

"Our guidance is that you need to get off XP. It's really that black and white," says Tom Murphy, Microsoft's spokesman handling the end of XP support. The company's party line is that Windows 8.1—the latest in Microsoft's foray into touch-friendly interfaces—is a "fully modern operating system."