There are already signs that Apple is not immune from the economic downturn. Mac sales, which outpaced Windows PCs for months, fell behind the latter in January at U.S. retailers, according to the NPD Group.

Mac sales, desktops and notebooks combined, fell 6% in terms of units sold compared with the same month a year ago, and 11% in terms of revenue, NPD said. Windows PC sales, on the other hand, were up 13% in terms of units, while revenue was flat as consumers sought out less-expensive models.

NPD attributed the drop in Mac sales to Apple's higher prices and the fact that the iMac line hadn't seen a refresh since April.

Apple zeroed in on the latter with the latest releases. All the iMacs have dual-core Intel processors with clock speeds ranging from 2.66 GHz in the least-expensive models to 3.06 GHz in the top of the line. Memory is expandable to up to 8 GB, hard drives range from 320 GB to as much as 1 TB, and all but the two most expensive systems come with the GeForce 9400M. The remaining two include a higher-performing Nvidia GeForce GT 120 processor in one of the systems and a GeForce GT 130 in the most expensive model.

All the iMacs have a glossy display with a built-in video camera, microphone, and speakers in a thin aluminum and glass design. They also include built-in support for Bluetooth and 802.11n Wi-Fi wireless networks, and all the systems come with iLife '09, Apple's suite of consumer applications for managing and organizing photos, making movies, and creating and learning music.

Prices start at $1,199 for a 20-inch model, topping out at $2,199 for the highest performing 24-inch system.

The update of the Mac Mini was long overdue, given the system has gotten little attention from Apple since its release in the summer of 2007. While the price still starts at $599, the baseline system includes a 2-GHz Intel Core 2 Duo processor, 1 GB of DDR3 memory, a 120-GB hard drive, and built-in Wi-Fi and Bluetooth support.

Finally, Apple also released new versions of its AirPort Extreme 802.11n Wi-Fi Base Station and the Time Capsule backup system for the Mac. Both feature simultaneous 2.4-GHz and 5-GHz dual-band networking. The Time Capsule is available in two models: a 500-GB system for $299 and a 1-TB model for $499. The AirPort Extreme sells for $179.

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