"When you go out and buy a new machine, I'm not sure you want it with an 8-year-old operating system," Gillen noted. Most consumers will want to "move forward rather than look backward," he said.

"I think it's better for customers not to go back," Cherry agreed. Even though Microsoft will continue to support XP, consumers will be better off going with the newest OS, which also is the one Microsoft is actively maintaining, he said.

However, savvy consumers who really want to buy new machines with XP can still get it several ways. They can simply go to Dell's Web site and order one of the business PCs, which come with Vista but can be downgraded to XP, Gillen said.

In addition, Microsoft will continue to allow the low-cost laptops to ship with XP.

Microsoft is also allowing small specialty PC builders to sell computers with XP through January 2009. Consumers may also see shrink wrapped copies of the software and even PCs with XP in stores for a while as the shops empty inventory, Microsoft said.

But while consumers may happily buy Vista, stories of enterprise resistance continue to pop up. Notably, Microsoft partner Intel recently said that XP is and will be by far the dominant OS for the bulk of Intel's 80,000 employees. The company is testing and deploying Vista in certain departments, it said.

Enterprises are perhaps more aware of the technical issues that plagued Vista at launch, and they want to be sure that any new OS will work well with existing software investments.

Microsoft continues to encourage enterprise customers to upgrade. In a letter sent a week before June 30 to business users of Windows, Bill Veghte, Microsoft senior vice president of online services and the Windows business group, laid out the ways that enterprises can continue to use XP and also described reasons that they should upgrade to Vista.

He acknowledged the early issues Vista had at launch and said they've been addressed. "The architectural changes that improved security and resilience in Windows Vista led to compatibility issues with existing hardware and applications," Veghte wrote. "Many hardware drivers and applications needed to be updated, and while the majority worked well when we launched Windows Vista, some key applications and drivers were not yet available." Vista now supports twice as many components and devices as it did at launch, he said.

According to a spokeswoman from Microsoft's public relations firm, there is no deadline for the XP downgrade offer for business customers. There is a deadline, however, for when Microsoft will supply XP discs to the manufacturers to include in the box with a new PC. After January 2009, if a business customer wants to downgrade to XP, it will have to work directly with Microsoft to do so.