Essentially, Vista is fooled into upgrading itself, thus allowing customers to avoid the need to have a prior copy of Windows XP or 2000 installed on that computer. While time-consuming because of the double installation, advocates say this workaround not only allows users to do a fresh install of Vista, which they say will run more reliably, but can save some customers money. The amount depends on which flavor of Vista a customer gets.

The difference between the full and upgrade price of Vista Home Basic is US$100 ($199 vs. $99). For Vista Home Premium, it is $80 ($239 vs. $159). For Vista Business, it is also $100 ($299 vs. $199). For Vista Ultimate, it is $140 ($399 vs. $259).

A Microsoft spokeswoman said in an e-mail that the company is "well aware of the workaround," which she added "violates the terms of use agreed to when they purchased the upgrade version of Windows Vista. As such, we believe only a very small percentage of people will take the time to implement this workaround, and we encourage all customers to follow our official guidelines for upgrading to Windows Vista, which can be found at www.WindowsVista.com, instead."

Microsoft is right: for most businesses as well as consumers, the workaround will prove to be irrelevant. Why? Because most larger corporations buy Vista in volume licenses, which are usually discounted off the list price. Also, the time involved in having IT staff manually installing Vista twice on each PC would more than outweigh any potential cost savings.

For consumers and small businesses, the vast majority will get Vista pre-installed when they buy a new PC. Buying a new PC without an operating system on it and then installing an upgrade version of Vista might actually cost more than buying a new Vista PC because of the low price Microsoft charges OEMs to pre-install Vista, along with other discounts that it offers.