Something big: 27-inch iMac

Apple's all-in-one computer, the iMac, has always done a good job of putting the customer's focus where it belongs: on what's happening on the screen. Even though the iMac could hold its own in any museum, you're interacting with Mac OS X and the software.

With Apple's latest revisions to the iMac, you couldn't escape the screen if you tried. Maxing out at 27 inches and 3.6 million pixels (or 21.5 inches for the entry-level configuration), the iMac just might be larger than your television — and that's no coincidence.

I tested a 27-inch iMac powered by a 3.06 GHz Intel Core 2 Duo processor with 4 GB of memory and an ATI Radeon HD 4670 graphics card with 256 MB of memory.

Apple also offers a configuration of the 27-inch model containing a 2.66 GHz Intel Quad-Core i5 processor (or, as a build-to-order option for an extra $200, a 2.8 GHz Quad-Core i7 processor), but that model was not yet shipping.

Pricing for the iMac is more aggressive in this revision: the stock 21.5-inch models are priced at $1,199 and $1,499, while the 27-inch configurations sell for $1,699 and $1,999. (Several build-to-order options are also available at extra cost.)

Immersive field of view. The 27-inch screen is a giant, especially if you're accustomed to smaller consumer displays. I've used Apple's 30-inch Cinema HD Display on a few occasions, and this 27-inch screen feels comparable.

The display also gains a wider field of view — 178 degrees — by employing IPS (in-plane switching) screen technology, so you don't see the kind of color shift or brightness change evident on older displays when you look at them from an angle.

The screen is glossy, and there's no option for a matte version, so you'll need to be mindful of reflected light sources. My office is fairly dark with the rear of my desk facing an internal window, so reflections didn't bother me, but I know some people for whom the glossy screen is a major limitation.

The LED backlighting is bright and responsive, and high-resolution photos look great full screen.

What's funny about the 27-inch screen is that Apple's own HD video offerings through the iTunes Store, which top out at 1280 x 720 pixels, come up short on such an expanse of pixels. Viewing an iTunes HD movie full screen, for example, causes a little blurring from upsampling the image.

Then again, as my mother would say when I was a kid, you probably shouldn't be sitting so close to the screen to watch a movie anyway. The large screen reveals some other features, the most curious of which is the capability to use all of that resolution as a second monitor.

When you connect the iMac to a recent Mac using a cable with Mini DisplayPort connectors on each end, the iMac automatically switches to Target Display Mode. So, for instance, plugging in a MacBook Pro extends your desktop to cover both the iMac's screen and the laptop's built-in display.

The iMac continues to run in the background. Anticipating that people would use the iMac as an entertainment center, Apple designed the mode so that all keys except media controls on the keyboard are disabled when another machine is connected, so you can continue to listen to music. Pressing Command F2 toggles the display between Target Display Mode and the iMac's own screen.

Performance. Although I didn't run a fleet of benchmark tests (I'll leave that task up to dedicated labs such as those at Macworld), I did find the iMac to be speedy in handling digital photos, playing "Call of Duty 4" at high resolution and detail settings, and just engaging in everyday usage.

I also set up an action in Photoshop CS4 that applied several adjustments to an image (resizing, rotating, and applying filters to a file), and then batch-processed roughly 1 GB of digital photos. The iMac completed the task 14 percent faster than a current 15-inch 2.66 GHz Core 2 Duo MacBook Pro, and 25 percent faster than my 2.33 GHz Core 2 Duo MacBook Pro from late 2006.

Those are solid, though not groundbreaking, improvements. I expect today's buyers will see a bit better performance over time as third-party applications take advantage of the technologies such as Grand Central Dispatch and OpenCL introduced in Mac OS X 10.6 Snow Leopard.

It's noteworthy that Apple includes the quad-core i5 and i7 processors in the consumer-level iMac. Apple claims a twofold performance increase over the models running the Core 2 Duo processors, depending on the application.

Companies or individuals who need a powerful machine but don't want to spend the extra money for a Mac Pro system can turn to the high-end iMac instead.

Magic Mouse. The new iMac is the first Mac to include Apple's new Magic Mouse, a wireless sliver of technology that's the first Apple mouse in a long time that I'm comfortable using.

As with the retired Mighty Mouse, the entire top surface clicks as a mouse button press, instead of having discrete buttons. It also includes sensors that can differentiate between a left-click and a right-click.

But on the Magic Mouse, the top surface is also entirely touch-sensitive. Instead of using a scroll wheel, drag a finger anywhere on the surface to scroll. My favorite feature is scrolling with momentum, which continues scrolling a page after you've lifted your finger until the calculated physics slow the motion to a stop.

You can also swipe left or right with two fingers to navigate items such as going to the previous page in a Web browser window. The motion is a little tricky at first — I kept pressing when I should have been gliding, and ended up flinging the mouse across the desk a few times.

The Magic Mouse isn't equivalent to a Multi-Touch trackpad found on Apple's portables; you can't tap just the surface to click, pinch to zoom, or use other gestures. It also doesn't support some of the Mighty Mouse features such as pressing two buttons at once to launch Exposé.

The newest iMacs are more powerful, sure, but the real draw is going to be the screen and its possibilities. The danger for me is that after having that giant expanse of pixels available to me, I won't want to go back to my relatively tiny 15-inch laptop screen and 20-inch external display.

Jeff Carlson contributes to the Practical Mac column in Personal Technology.