Apple on Monday refreshed its iMac line with faster Intel Core 2 Duo processors and an optional more powerful graphics processor on its high-end 24-inch model.

The new iMac is available in three basic configurations: a 20-inch 2.4-GHz model ($1,199), a 20-inch 2.66-GHz model, and a 24-inch 2.8- GHz model. The 2.4-GHz iMac comes with an ATI Radeon HD 2400 XT (128-MB memory) while the 2.66-GHz and 2.8-GHz models come with an ATI Radeon HD 2600 PRO (256-MB memory).

There's also a built-to-order 24-inch 3.0-GHz model featuring Nvidia GeForce 8800 GS (512-MB memory) that lists for $2,199 at the Apple Store, with 2 GB of memory and a 500-GB hard drive.

The new Intel Core 2 Duo processors that power the iMacs feature a 1,066-MHz front-side bus and can be configured to support up to 4 GB of 800-MHz DDR2 SDRAM memory.

Apple's iMacs include built-in AirPort Extreme 802.11n Wi-Fi networking, Bluetooth 2.1+EDR, Gigabit Ethernet; a built-in iSight video camera; five USB 2.0 ports; one FireWire 400 port; and one FireWire 800 port. They also come with Apple's iLife consumer media suite and Apple's Mac OS X 10.5.2, known as "Leopard."

According to Apple, its new iMacs are rated EPEAT Silver and meet the Energy Star 4.0 requirements for power consumption.

EPEAT, the Electronic Product Environmental Assessment Tool, is a program run by the Green Electronics Council that attempts to encourage environmentally responsible electronics manufacturing. It lists 23 required criteria and 28 optional criteria that are used in determining whether products qualify for the organization's Gold, Silver, and Bronze ratings. The Silver designation means a product must meet all 23 required criteria and at least 50% of the 28 optional criteria.

Federal acquisition rules require that 95% of computers purchased comply with EPEAT criteria; as of April 2008, San Francisco city departments may only purchase computers and monitors that are rated EPEAT Silver or Gold.

Apple's new iMac arrive on the heels of another in a series of strong quarterly financial reports. Last week, Apple reported revenue of $7.51 billion and net quarterly profit of $1.05 billion, a 43% increase year over year.

Apple said that it shipped 2,289,000 Macintosh computers during the first quarter of 2008, a 51% increase over the same quarter in 2007.

In a statement on Monday, Apple's senior VP of worldwide product marketing Philip Schiller noted that Mac sales have been growing at a rate 3-1/2 times faster than PC sales.

Earlier this month, research firm IDC reported that Apple's share of the U.S. PC market during the first quarter of 2008 reached 7.1%, up from 4.9% in the first quarter of 2007, representing 45% growth. Dell's share of the U.S. PC market during this period reached 30.9%, up from 27.7% in the first quarter of 2007, representing 15.6% growth.