The PC market looks like it's headed for a bad year, as notebook sales fall prey to Apple's iPad and other tablets.

Acer warned this morning that first quarter sales 10% from last year, and it doesn't expect any growth in the second quarter either. It previously expected 3% sales growth for the quarter.

The Taiwanese computer maker also said that revenue for the first two months of 2011 was down almost 36% from the previous year.

The obvious reason: Acer specializes in low-cost notebooks, including netbooks. Those computers have been devastated by the rise of tablets -- particularly Apple's iPad. The company is introducing new tablets later this year, including some that run Google's Android operating system instead of Windows, which could help reverse the slide.

Acer's Android tablets won't help Microsoft, whose Windows OS still powers more 90% of PCs sold, but has much less traction in touch screen tablets. Microsoft has earned about $13 billion on nearly $18 billion in Windows sales in the last four quarters, but admitted that it's seeing some weakness in sales of low-end PCs.

Acer's warning is just the latest mark against the traditional PC industry: earlier this month, research firm Gartner cut its PC sales forecast for 2011 from 400 million to 388 million, and Best Buy reported a fall-off in notebook computer sales in its earnings report yesterday.

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