• by Sarah Mahoney  @mahoney_sarah, January 7, 2011

Best Buy says comparable-store sales fell 5% in December, with declines in entertainment software and TVs offsetting growth in mobile phones and appliances. And while the Minneapolis-based chain says the results were within the range of its expectations, the disappointing results are further evidence that tech sales weren't the Christmas present many retailers were hoping for.

In fact, the NPD Group reports that tech sales weakened across all channels. The Port Washington, N.Y.-based market research company says that despite the heavily promoted specials that started early in November, it estimates the nine-week holiday period will come in with some $14.9 billion in sales, 4% below the prior year.

"Record sales in 2009 across major categories such as notebook PCs and TVs, combined with a significant slowdown in the pace of price declines, created a difficult headwind for the industry in 2010," the company says in its report. And while smartphones, e-readers and tablets were all bright spots, those gains couldn't make up for decreases. While TV sales actually gained, for example -- with unit sales of flat-screen models climbing 5% and plasma sales jumping 32% -- revenue for each type declined.

PCs struggled. First, comparisons were difficult, since a crop of appealing netbooks, as well as the launch of Windows 7 juiced the previous year's sales. Second, tablets -- with their considerable Internet capabilities -- may be cannibalizing as much as 15% of computer sales, NPD says. Notebook unit volume fell 9% in the holiday period, netbook sales fell 38%, and desktops fell 16%.

"Tech consumers ignored early-season promotions, and instead keyed in on the traditionally price-aggressive deals offered during Black Friday and the week before Christmas. As a result, sales for the first three weeks of November and the first three weeks of December were significantly weaker than the traditional bookmark shopping periods," it says. Still, a few smaller categories sparkled: Unit sales of stereo headphones soared 30%; DSLR cameras gained 16%; and Blu-ray rose 27%.

But many of the smaller gadgets that buoyed sales in Christmases past fizzled: In the point-and-shoot camera realm, sales fell 9%, MP3 players dropped 8% and GPS units tumbled 24%, NPD reports.

For Best Buy, the best news came from mobile phones, with smartphones fueling a low-double-digit increase in sales. Appliances sales were up smartly, with a 10.9% comparable-store increase, and the chain's service category, including the Geek Squad, posted a 7.6% gain.