SEATTLE (AP) -- Chris Pirillo leaned away from his webcam and pointed to his printer/scanner/fax machine, which stopped scanning and faxing after he installed Microsoft Corp.'s new Windows Vista operating system.

''I can't live in Vista if the software that I use in my life for productivity does not work,'' said Pirillo, in the third minute of a 52-minute video he posted on YouTube.

Nearly six months after it launched, gripes over what doesn't work with Vista continue, eclipsing positive buzz over the program's improved desktop search, graphics and security.

With Vista now shipping on most new computers, it's all but guaranteed to become the world's dominant PC operating system -- eventually. For now, some users are either learning to live with workarounds or sticking with Vista's predecessor, Windows XP.

Pirillo is geekier than the average user. He runs a network of technology blogs called Lockergnome, and was one of several ''Windows enthusiasts'' Microsoft asked for Vista feedback early on.

Still, Vista tested even Pirillo's savvy. He fixed the hobbled printer and other problems by installing VMware, a program that lets him run XP within Vista. But when his trial copy expired, he decided the solution was too clunky -- and too expensive.

He ''upgraded,'' as he called it, back to XP.

Users' early complaints aren't likely to threaten Microsoft's dominance in operating systems. The various flavors of Windows today run 93 percent of PCs worldwide, according to the research group IDC. Last fiscal year, Windows accounted for about a third of Microsoft's total revenue of $44.3 billion.

Industry analysts say Vista adoption is plodding along as expected, with most consumers and businesses switching over as they replace old hardware with new. IDC analyst Al Gillen said he expects Vista will be installed on the vast majority of computers in about five years, the time it took for XP to reach 84 percent of PCs.

It's too early for industry watchers to know exactly how many people are using Vista. At the same time, it's hard to gauge Vista's success by comparing it to XP, because the PC market has grown tremendously in the last six years.

In early May, Microsoft said it had distributed 40 million copies of Vista, which costs $199 to $399 depending on the version. But it did not specify the number actually sold through to consumers, versus those shipped to computer makers like Hewlett-Packard Co. and Dell Inc.

Analysts noted that as many as 15 million of those copies could represent upgrade coupons given to XP buyers during the holidays, before Vista went on sale. Microsoft would not say how many of those customers installed the program, but Forrester Research analyst J.P. Gownder estimated just over 12 million U.S. consumers would have Vista by the end of the year, out of about 235 million PCs in the country.

As for the compatibility problems, 2 million devices -- such as cameras and printers -- now work with Vista, said Dave Wascha, a director in the Windows Client group.

''We are way ahead with Windows Vista right now than where we were when we shipped Windows XP,'' he said.

Still, it's an uphill battle: Vista interacts differently with programs and peripherals than previous versions of Windows, and some companies have chosen not to spend time and money updating older products. Printer makers, Wascha noted, draw profits from ink cartridges and services, and have little motivation to invest in updating drivers for old hardware.