Apple Macs in U.S. retail stores fell behind Windows PCs in sales growth last month, an indication that Apple's strategy of charging more for its critically acclaimed design may be showing weakness in the economic downturn.

In-store Mac sales, including Apple stores, was flat in November compared with the same month a year ago, while sales of Windows PCs rose 7%, according to The NPD Group. The biggest drag on Mac sales was the desktop segment.

Sales of Mac desktops plummeted 38%, while Windows desktops were down 15%, NPD said Tuesday. Overall, the desktop market was down 20% from a year ago.

In the notebook segment, however, Apple sales outpaced sellers of Windows PCs. Apple laptop sales rose 22% from a year ago, compared with 15% for Windows systems. Overall, laptop sales were up 16.6%.

Nevertheless, Apple saw a drop in its share of overall units sold in retail stores. The company's share fell to 15% from 20% in October and 16% a year ago, NPD said. Apple's desktop share fell to 15.8% from 17.4% in October and 20.6% a year ago.

Apple's notebook share was more positive. The company had a 14.8% share in November, compared with 14.1% a year ago. Apple's share, however, was down from 20.9% in October, when new MacBooks gave a boost to sales.

Overall, the numbers are an indication that Apple may be feeling the competitive pressure of Windows PC vendors, such as Hewlett-Packard and Dell, which have reduced prices at much larger percentages than Apple to boost sales in the economic slowdown, analysts say. In addition, a new category of mini-laptops, or netbooks, with prices as low as $300 also may be having an impact, particularly in the education market.

The PC industry as a whole has certainly felt the impact of the world recession. Market researcher IDC this month slashed its 2009 PC revenue forecast, saying the market would fall by 5.3%. The analyst firm had predicted growth of 4.5%.