• by Mark Walsh  @markfwal, January 5, 2011

The last six weeks have seen a steady stream of upbeat reports about 2010 holiday retail sales, both online and offline. Overall U.S. retail sales during the season -- between Nov. 5 and Dec. 24 -- went up 5.5% compared to a year ago, according to the final tally from MasterCard SpendingPulse, a unit of MasterCard Advisors that tracks sales by all payment types.

On Wednesday, comScore said online holiday sales were up 12% from last year to a record $32.6 billion as retailers benefited from beginning promotions earlier than in prior years. But not every retail category was sharing in the seasonal cheer, as consumer electronics sales fell 5% from a year ago, according to findings released Wednesday by NPD Group.

The research firm attributed the slide to weaker demand for products such as flat-screen TVs and netbook PCs. "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," said Stephen Baker, vice president of industry analysis at NPD, in a statement.

In contrast to comScore, NPD said consumers ignored early-season promotions and instead focused on deals offered on Black Friday -- typically considered the start of the holiday shopping season -- 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," said Baker.

It's important to keep in mind that NPD's consumer electronics category doesn't include mobile devices or video game players -- so hot electronics products like tablets, e-readers and smartphones are not included in the total.

TVs were not being snapped up at the rate of last year. Flat-panel unit sales rose 5%, but revenue was off 2% as retailers cut prices heavily to move stock. Unit sales of plasma TVs, for instance, were up 32%, but revenue fell 8% as average prices dropped almost 15% to $728. The 32-inch LCD, last year's hot product, was not nearly as popular in 2010, with unit volume dipping 2%, according to NPD.

Sales of TVs above 50 inches, however, saw strong growth with volume jumping 21% -- with consumers enticed by new technologies such as 3D, Internet connectivity, and LED backlighting. In a separate report released last week, NPD found that 45% of consumers who say they have an Internet-connected TV are using the broadband features and most are happy with the results.

PCs in 2010 suffered a letdown after the buzz around netbooks and the launch of Windows 7 last year. NPD estimates tablets like the iPad and Samsung Galaxy took as much as a 15% bite out of the PC market, equating to almost 1 million unit sales during the holidays. Netbook unit volume tumbled 38% from a year ago, and desktop unit sales dropped 16%.

Among categories that fared better were stereo headphones, which saw 30% unit and 48% dollar increase over 2009, while Blu-ray unit volume was up 27%.