Tales of smartphones and tablets eating into more traditional computing have been largely anecdotal -- until now.

Shares of Microsoft (Nasdaq: MSFT), Hewlett-Packard (NYSE: HPQ), Dell (Nasdaq: DELL), NVIDIA (Nasdaq: NVDA), and even Intel (Nasdaq: INTC) opened lower this morning, after a grim report on the state of PC sales.

Industry tracker IDC is reporting a 3.2% year-over-year decline in global PC shipments during the first three months of 2011. It's the first quarterly dip since the end of the recession. Things get even uglier closer to home, where healthy gains by Apple (Nasdaq: AAPL) and Toshiba weren't enough to send stateside shipments plunging by a sharp 10.7%.

IDC points to the upheaval in the Middle East and natural disasters in Japan as possible reasons for the shortfall, even though the global economy appears to be holding up with its end of the bargain.

There's something else happening, and IDC does address the 800-pound Android gorilla in the room.

"Good-enough computing has become a firm reality," senior research analyst Jay Chou points out in the press release.

Of course. Companies aren't running spreadsheets on Android smartphones. Die-hard gamers may take some time before embracing the iPad. However, Web-savvy handsets and tablets are redefining the way many of us compute casually. A home that used to have a computer and a laptop could logically swap one out for a tablet.

It's happening, especially here in the United States. If anyone argues that the iffy stateside economy is to blame for desktop and laptop sales waning, ask them to explain why smartphone and tablet sales took off last year. Computing devices are being replaced with gadgets that are not as powerful or perhaps even as functional, but they are clearly more portable and fun to own.

Some of the PC-centric stocks taking a hit today should bounce back. Intel isn't going to miss out on the "good-enough computing" revolution. Graphics chip designer NVIDIA has even better seats and has moved firmly positive as of this writing. However, they won't all rebound. HP and Dell have struggled in the smartphone and tablet markets. Microsoft's operating system stronghold is a distant player in mobile -- and don't even ask about the tablet space.

If the trend continues -- and it will until tablets are exposed as a novelty or consumers need more computing power -- it may be dangerous to own some of the computing giants that seemed to have it all in the 1990s.

Will PC shipments bounce back? Share your thoughts in the comment box below.

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Longtime Fool contributor Rick Munarriz pecked away this article on an HP computer, but he does not own shares in any of the companies in this story. He is also part of the Rule Breakers newsletter research team, seeking out tomorrow's ultimate growth stocks a day early. The Fool has a disclosure policy.