Normally, a speedier computer that appears to be carbon copy of the one it replaced isn't worthy of much attention.

Paul Sakuma, Associated Press
Apple Computer workers test the Apple iMac powered by an Intel processor at the MacWorld conference in a San Francisco earlier this month.
Click photo for larger image.

Not so, with the new iMac from Apple Computer Inc., the first with silicon brains from Intel Corp.

The new iMacs remain visually stunning, with the entire computer squeezed into the frame of a 17-inch or 20-inch flat-panel display. They still have built-in video cameras. They run most of the same software titles. And they cost the same ($1,299 or $1,699) as the last generation of iMacs, which ran IBM's PowerPC chips.

Given all that could have gone wrong in the historic chip switch, all this similitude is significant.

The Intel Corp. Core Duo processor inside, with two computing engines on each chip, does deliver a boost in performance with some programs, though Apple's claims of up to three times over the last generation is a stretch.

The chips also don't kick off as much heat, suggesting they're consuming less power -- just as would be expected from a chip whose heritage is in notebooks.

More significant than the new chip itself is the impact of the transition on users.

Swapping such a key component isn't as easy as prying out the old and plopping in the new. Supporting chips also must be switched out, and every bit of software, from the operating system on up, must either be rewritten or translated on the fly.

It requires considerable skill, not to mention arm-twisting, to get users and software developers in the same boat.

Apple, at least so far, seems to have done a very good job at making sure all old programs run seamlessly on the new Mac and that its new programs run on older Macs.

With very few exceptions, no one should feel abandoned.

I borrowed a 20-inch Intel-based iMac from Apple and installed a variety of software on it, including programs optimized for the new systems and some that I had bought for my five-year-old Power Mac.

A number of Apple's applications, including the latest versions of Mac OS X, iWork '06 productivity suite and the iLife '06 bundle of multimedia applications, already are available as "Universal" applications that work with both Intel and PowerPC Macs.

On the new Mac, the operating system was snappy. Programs like iPhoto, iTunes, Pages and Keynote were similarly responsive and felt like they benefited from the boost in computing horsepower. The Web browser Safari also seemed zippier than usual, though that has more to do with the speed of my Internet connection than the processor.

The new programs also ran well on my older, PowerPC-based system.

In another test, I dug up copies of old programs and installed them on the new iMac. In this case, a technology called Rosetta takes over behind the scenes and translates the old code into something the Intel chip can understand.

As might be expected, there was a performance hit.

After installing the former Macromedia Inc.'s Studio MX 2004, I definitely noticed a slight lag when menus or windows were opened. It was most evident when moving complex pieces in the graphics program Freehand. That forced the image to redraw -- very slowly -- on the screen.

The speed declined further after I removed 512 megabytes of memory from my test system. (The box arrived with a gigabyte of memory, or double what's included in the system's $1,699 price tag.)

Other programs fared better. Microsoft Word, for instance, had no trouble keeping up with my typing.

Most consumers who use their machines to surf the Web, write e-mails and edit documents probably won't be bothered by the Rosetta slowdown. Advanced users and gamers will want to try out their favorite programs before buying one of the new Macs.

Apple has commitments from major developers to switch their programs over to Universal applications. The process will take some time, but it promises to keep owners of old and new Macs happy.

There are a handful of programs that won't work at all on the new Mac. They include some high-end professional applications from Apple, which promises to have new versions available within about a month, and also old programs that require Mac OS 9 and earlier.

The no-run list also includes Microsoft's Virtual PC, which allows users to run Windows on top of Mac OS X. It's not clear when, or if, Microsoft will update it.

Some might wonder if the new iMacs, because they have the same brain as computers that run Windows, can run that operating system. Right now, with Windows XP, the answer is no, though Apple says it won't prevent users from doing so.

The biggest stumbling block appears to be the software that boots up the machine. Apple uses a new Intel technology that dramatically speeds up the startup process. It's not supported in current versions of Windows, though the next version will.

The new Mac also sports other internal improvements. Its graphics card has been souped up and, on the 20-inch iMac, is memory upgradeable. The video subsystem also now supports extending the monitor to a second display. Previous iMacs only allowed mirroring.

All in all, the first Intel-based Macs are a promising start to Apple's faster-than-expected transition that put Intel chips in all its computer lines by the end of the year.

It's fitting that the transition started with the very product line that kicked off Apple's renaissance in 1998.

Once again, the iMac is leading the way and, for now at least, in the right direction.

First Published: January 29, 2006, 5:00 a.m.