Last week, two notable changes to , available now. First, all iMacs now use Intel's new 64-bit , which Apple claims can deliver up to 50 percent faster performance than previous Core Duo processors. However, in  on PC laptops, the Core 2 Duo chip improved performance by only 5 to 10 percent over identically configured laptops with the older Core Duo chip;  rated a 10 percent improvement. My guess is that the new iMacs with the Core 2 Duo will be faster, perhaps noticeably so in some tasks, but not so much that it would make sense to upgrade from an existing Core Duo-based iMac to a new Core 2 Duo-based model.
However, the second notable change in the iMac line may be sufficiently compelling to cause even a recent iMac purchaser to consider trading up to a new model. That's because the top-of-the-line iMac now comes with running at 1920 by 1200 pixels (compare that with 1440 by 900 for the 17-inch display and 1680 by 1050 for the 20-inch model). The 24-inch display also offers a wider viewing angle than the smaller displays, is brighter, and provides a higher contrast ratio than the 17-inch display (though slightly lower than the 20-inch display).
Interestingly, there are between the 24-inch iMac and the smaller models besides some added size and weight. The 24-inch iMac uses a faster Nvidia GeForce 7300 GT graphics processor (or an optional Nvidia GeForce 7600 GT) in favor of the Intel GMA 950 (in the 1.83 GHz 17-inch iMac) or the ATI Radeon X1600 (in the 2.0 GHz 17-inch iMac and the 20-inch iMac). Instead of a pair of FireWire 400 ports, the 24-inch iMac features one FireWire 400 port and one FireWire 800 port. It also doubles the power of its internal digital amplifier from 12 watts in the 17- and 20-inch iMacs to 24 watts.
A Plethora of Possibilities -- Configuring an iMac is a bit more confusing than in the past, since the low-end 1.83 GHz 17-inch iMac, priced at only $1,000, can be configured only with more RAM (512 MB standard, up to 2 GB), with an Apple Remote, and with a modem. It comes standard with a Combo drive, a 160 GB hard drive, Intel GMA 950 graphics processor, and AirPort Extreme, but not Bluetooth. This basic configuration was introduced in July 2006 for education buyers (see " ", 10-Jul-06); it's now available to anyone (and it still costs $900 for educational customers).
The 2.0 GHz 17-inch iMac ($1,200) can be upgraded to a 2.16 GHz Core 2 Duo processor and comes with a 160 GB hard drive, upgradable to 500 GB. In contrast, the 20-inch ($1,500) and 24-inch ($2,000) iMacs both come with a 2.16 GHz Core 2 Duo processor, upgradable to 2.33 GHz, and they both have 250 GB hard drives, with 500 GB options. All three of these models come with an 8x double-layer SuperDrive, 1 GB of RAM (upgradable to 3 GB), and built-in AirPort Extreme and Bluetooth 2.0.
Standard equipment for all iMac models includes a built-in iSight camera, three USB 2.0 ports, two FireWire ports, Gigabit Ethernet, mini-DVI out, built-in stereo speakers, a built-in microphone, optical digital audio in/out jacks, Mac OS X 10.4 Tiger, and iLife '06.
Mac mini Speed Bumped -- Although the also-updated Mac mini doesn't share the iMac's switch to the Core 2 Duo chip, , dropping the Intel Core Solo processor entirely while keeping prices at their previous level. The $800 Mac mini moves from a 1.66 GHz Core Duo processor to a 1.83 GHz Core Duo processor, and the $600 model drops its 1.5 GHz Core Solo processor in favor of a dual-core 1.66 GHz Core Duo processor. All other specs remain the same.