It was a rough holiday season for computer makers not named Acer. Industry-watching specialist Gartner is out with its preliminary PC shipment tallies, and they aren't pretty.

Stateside computer shipments fell by a whopping 10.1% to 15.6 million during the fourth quarter, according to Gartner. Market leader Dell (NASDAQ:DELL) led the slide, with a steep 16.4% reduction in shipments during the quarter.

Company

Q4 2008
Market Share

Q4 2007
Market Share

Year-over-Year
Shipment Growth

Dell

28.6%

30.8%

(16.4%)

HP

27.5%

25.6%

(3.4%)

Acer

15.2%

8.8%

55.4%

Apple

8%

6.7%

8.3%

Toshiba

6.5%

5.2%

12%

Others

14.2%

23%

(44.4%)

Source: Gartner.

Hewlett-Packard (NYSE:HPQ) closed the gap with Dell, setting the stage for an interesting battle for the gold in 2009. Apple (NASDAQ:AAPL) appears to be holding well, growing within a shrinking market, but hold the applause.

Three months ago, Apple was the speedster. It was the third-largest player in stateside shipments with 9.5% of the market. Acer missed out on the bronze back then, given its 8.9% slice. Apple's shipments were growing at a torrid pace of nearly 30% over the previous year's showing. Momentum has clearly shifted in favor of Acer's netbook stronghold.

Naturally it's worth pointing out that Apple's premium Macs and MacBooks sell for substantially more than Acer's devices. It's not fair to lean on a unit shipment table as gospel, when Apple would likely blow Acer away in terms of raw value of these computers. However, can Apple afford to stay out of the netbook market if the trend continues?

Apple bulls would argue that it would be counterproductive to throw its hat into a cannibalistic ring that would eat into its margins, validate a niche industry, and come at the expense of its higher-end machines.

I don't entirely agree. If Apple netbooks catch those who were angling for an Acer Aspire -- and not a pricier entry-level MacBook -- it can be incremental.

Now that even RadioShack (NYSE:RSH) is selling a connectivity subscription-tethered Acer netbook for $99.99 and Amazon.com's (NASDAQ:AMZN) best-seller list is flooded with netbooks, Apple can't ignore what the market is clamoring for.

A few years ago, when you had to squint your eyes to see the market share sliver that Apple was commanding, it could afford to thumb its nose at the masses. It's different now; Apple stores dot suburban shopping malls. It has to respond, or retreat back to its niche nook. Now that everyone wants to "think different," Apple has no choice but to be the same.

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Longtime Fool contributor Rick Munarriz settled for a Dell laptop instead of a MacBook three months ago, based partly on price. 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.