Market research firm NPD Group reports that Apple took the top spots in U.S. desktop and laptop retail sales categories for the month of October. Apple’s refreshed iMac line and its laptop computers occupied top spots. The news comes by way of Cnet.

October saw the introduction of new 21.5-inch and 27-inch iMac models. The 21.5-inch model was the best-selling desktop that month, with the 27-inch iMac occupying the number three spot.

NPD vice president of industry analysis Stephen Baker told Cnet that Apple’s strong chart showing was helped by an otherwise down month on the Windows desktop side, as vendors pushed existing inventory before Microsoft’s launch of Windows 7.

Apple’s $1,199 13-inch MacBook Pro model also took the top spot. Apple also occupied the number 8, 9 and 10 slots for the month in laptop sales.

Baker suggested that Apple laptop sales were similarly aided by Windows retail doldrums prior to Windows 7’s launch. Microsoft released Windows 7 on October 22, 2009.

NPD didn’t provide a list of the other computer accounted for in the top ten lists. The numbers are culled from online and retail store sales, but does not account for direct sales, according to the report.