Despite the criticism leveled at Microsoft after the recent rollout -- and rollback -- of Windows Genuine Advantage (WGA), experts say that effort was just the first phase in the company's latest antipiracy effort, dubbed the Genuine Software Initiative.

In fact, the initiative -- which will include a similar campaign in the near term called Office Genuine Advantage (OGA) to fight piracy of Microsoft's dominant productivity software suite -- is tied in the long term with how Microsoft and other vendors will sell and deliver software.

"It's getting to the point where we're getting 'Advantaged' left and right," said Lauren Weinstein, a IT consultant and co-founder of the pro-privacy group People for Internet Responsibility. "The issue is, whose advantage is it?"

In early June, Weinstein publicly revealed via his blog that WGA was sending back data about users' computers every time they rebooted their PCs. That worsened WGA's already bad image: Users complained about WGA's tendency to stealthily install itself on some users' PCs, nag others who refused to install it, and falsely cry wolf with up to a fifth of the legitimately installed copies of Windows it scanned.

"A 20 percent false-positive rate is pretty abysmal," Weinstein said. Most victims have been gamers or PC hobbyists who have upgraded their hardware, which Microsoft has acknowledged can confuse WGA. But some have been businesses like S&S Cycle, a maker of motorcycle racing parts.

WGA repeatedly identified S&S's 180 PCs as running pirated copies of Windows, according to network administrator Karen Zander. Worse, it sent that data to Microsoft every morning as employees arrived in the office and turned on their PCs.

"Our network came to screeching halt," said Zander, who eventually fixed the bug by working with Microsoft technical support.

Such complaints, along with two class-action lawsuits, forced Microsoft to pull WGA's most intrusive features and make it optional. Having learned its lesson with WGA, Microsoft is likely to proceed more cautiously with its Office counterpart, which it began testing in April.

"Microsoft has almost no competition with Windows," said Joshua Erdman, president of software reseller Digital Foundation. "With Office, it's a lot easier to switch to something like OpenOffice or StarOffice. So Microsoft can't afford to [anger] people as much."

OGA, for now, consists of an ActiveX-based tool that users are invited to download on a voluntary basis the first time they get certain noncritical updates from Office. Like WGA's validation tool, OGA checks to see whether the license key is stolen or counterfeit. If it isn't, the tool stores a special download key on the PC to aid in future verification.

Adrian W. Kingsley-Hughes, a technology consultant who runs the blog The PC Doctor, said OGA mistook his legal copy of Office for a pirated one. "No idea why I had problems," he said. "I was quite surprised when it said it didn't check out."

A Microsoft spokeswoman declined to say how often OGA is wrong. But on its tech support Web site, Microsoft says that OGA can fail to validate a legitimate copy of Office XP or 2003 for a number of reasons, including if the PC's time is off by more than 24 hours, or if the registry is modified or damaged -- something that can be caused by a virus or spyware.

Microsoft declined to specify if and when it plans to make OGA mandatory. It is being tested with users now in eight languages, including English.

"We are absolutely committed to having Microsoft Office participate in the advantages of Microsoft's overarching Genuine Software Initiative but have nothing further to discuss at this time as the program has not launched worldwide," a spokeswoman said in e-mail. So far, OGA has resulted in few complaints.

"If in the future OGA is kept like this, then that's OK for me," said Guillaume Kaddouch, a French programmer whose free tool for removing WGA has been downloaded half a million times. Kaddouch said he has no plans to write a tool to remove OGA.

While some suggested that Microsoft has learned its lesson with the WGA brouhaha, others said Microsoft is unlikely to abandon the Genuine Software Initiative because it is central to the company's evolving software-distribution model.

Microsoft still makes virtually all of its money from selling software installed on individuals' or companies' computers. But as more companies move toward a software-as-a-service model, such as that offered by Salesforce.com, and rent access to applications through the Internet, Microsoft has said it is likely to move toward a hybrid model.

Under that model, applications and data are partly installed on users' computers and partly accessed through the Internet. WGA-type tools that continually rescan and verify the computers of paid-up subscribers may become a necessary component of such hybrid applications.

But by putting the cart before the horse and making WGA mandatory before Microsoft has fully embraced this new software model could turn off loyal customers, Weinstein suggested.

"Microsoft is starting to tread a thin line that has quite an abyss on either side," Weinstein said. "If people feel that Microsoft is acting too aggressively, they will find some way to go to other products."