The latest pre-launch criticism of Windows Vista has come from Acer, one of the largest PC makers, which has revealed what it believes is the real purpose behind the proliferation of different Vista editions - to effectively raise Windows prices by 10 percent.

The most basic version of Vista, Home Basic, will cost around the same as the home edition of Windows XP. But the software is so stripped-down that many PC makers, including Acer, are not even planning to offer it. That leaves Home Premium as the lowest tier, according to Acer senior corporate vice president Jim Wong.

The new [Vista] experience you hear of, if you get Basic, you won't feel it at all," Wong said in an interview with PC Pro. "There's no [Aero] graphics, no Media Center, no remote control."

The quandary for PC makers is that Vista Home Premium, the next version up, costs 10 percent more for manufacturers than XP's Home edition. That is such a big jump that it adds 1 to 2 percent to the overall cost of manufacturing a PC, in an industry with wafer-thin margins as it is.

Wong believes consumers will demand Vista Home Premium but will not put up with higher PC prices, leaving manufacturers to absorb the extra costs.

Microsoft confirmed what Wong was saying. "We expect... that most home users will be purchasing Windows Vista Home Premium edition for desktop and mobile PCs," said a company spokesman.

However, the company defended Home Basic. "For those who simply want to use their PC for tasks such as surfing the Internet, corresponding with friends and family using email, or performing basic document creation and editing tasks, Windows Vista Home Basic delivers a safer, more reliable, and more effective computing environment."

Earlier this week, Microsoft admitted that some PC users would be put off by licensing enforcement measures built into Vista. Company spokesman Mike Burk said that Microsoft users who frequently change the hardware configuration of the system running Vista may fail Vista's new Software Protection Platform software-validation feature more than once. If they did, they would be required to purchase an additional license or use Microsoft's support services to activate Vista on a newly configured machine.

And an expert in software migration this week said there are even fewer reasons for businesses to upgrade to Vista than there were for upgrading to Windows XP. Rich Bentley, client and mobile manager for software developer Altiris, also attacked some market researchers for over-optimistic forecasts, in particular Gartner and IDC figures, which suggest that Vista could be in mainstream use by the end of 2007.