One week after refreshing its line of professional desktop computers,

Apple

(AAPL) - Get Report

on Tuesday upgraded its iMac line of consumer desktops.

The three base models of iMacs will have faster processors, bigger hard drives and more main and graphics memory than their predecessors. The new machines will also have built-in support for wireless and gigabit Ethernet networking; the previous models offered wireless network as an add-on.

The newest iMacs will also include the latest version of Apple's operating system, dubbed "Tiger," which Apple released last week.

Although Apple's sales and stock took off last year thanks to the popularity of its iPod line of digital music players, the company still gets the bulk of sales from its Macintosh desktop and notebook computers. In recent quarters, the company's iMac line has been the biggest sales generator in its computer segment.

Apple has won plaudits from critics for the iMac design. The computer line incorporates the processor, drive, ports and flat panel display all into a sleek rectangular shell.

The new line of iMacs will include either a 1.8GHz Power PC G5 or a 2.0GHz G5 processor. The hard drive will range from 160GB for the lower two models to 250GB on the top-end model. All three models will have 512MB of SDRAM and an

ATI

(ATYT)

Radeon graphics chip with 128MB of video memory.

On the previous line, which Apple introduced in August, the processor speeds were either 1.6GHz or 1.8GHz, and the hard drives ranged from 80GB to 160GB. Instead of the ATI graphics chip, the older iMacs used

Nvidia's

(NVDA) - Get Report

GeForce FX5200 graphics processor with just 64MB of video RAM.

Last week, Apple

unveiled similar processor and hard drive upgrades to its PowerMac line of professional desktops.

Analysts and investors have been hoping that the iPod's popularity will help boost the sale of Apple's Macintosh line of computers, luring in customers who either hadn't owned a computer before or who were users of PCs running

Microsoft's

(MSFT) - Get Report

Windows. Apple's overall computer sales have picked up in recent quarters, outpacing the overall PC market, but some analysts have questioned whether the company will be able to maintain its newfound momentum.

In recent trading, shares of Apple were off 18 cents, or less than 1%, to $36.25.