Buying Vista? Get a guarantee

It's hard to know if your PC is truly Vista-compatible, experts say. But some retailers are trying to cut the confusion.

Before spending the money for Windows Vista, set to debut this week, is there any guarantee that the software you buy will run as advertised on your PC? Not exactly, analysts say.

Microsoft does offer its , which scans computers for Vista readiness, indicates which of four versions will adequately run and makes upgrade recommendations, should hardware need help. CNET and other tech sites also offer free tools to analyze a PC's Vista readiness and version compatibility. Still, such tools won't absolutely certify that consumers will be able to run the version of Vista they pay for, analysts say.

"Just because a machine came back Vista-positive, I am not ready to make the assumption that all the features of Vista will run on this machine," said Michael Cherry, lead analyst for Windows and Mobile at Directions on Microsoft. His advice: "If it says (a PC) will run Vista, you still want to think about which features are important, and in talking to a vendor, you want to get an assurance that the unit (you are buying) will, in fact, accomplish those things you want."

While Microsoft's tool, and others like it, provide a general indication of whether a computer is Vista-compatible, they do not let users probe to see if specific features--such as or BitLocker drive encryption--will work, Cherry said.

Customers who pay about $233 for an upgrade copy of Vista Ultimate (or about $399 for the full version), for instance, could essentially end up running the equivalent of Vista Home Basic ($100 to $199) if Vista's installation software finds that the computer doesn't have the hardware to run specific Ultimate features optimally, Cherry said.

Microsoft's list of requirements for optimally running Vista Ultimate, the fullest version, or other versions, is long and detailed.

Vista buyers who find that their computer is not completely Vista-compatible will have few options. They can choose to spend additional money on upgrades to their computer, install fewer Vista features than they paid for or purchase a new PC that is fully compatible.

Cherry recommends against modifications and says consumers should instead purchase a new machine.

Michael Silver, an analyst at Gartner, agrees: "Joe Consumer is not generally equipped to upgrade an operating system. This is not a trivial matter." The market researcher estimates that roughly 40 percent of the 320 million consumer PCs worldwide running a previous version of Windows can run some version of Vista.

However, "some portion of that (percentage) will need at least memory upgrades," Silver said. Moreover, he estimates that only about 15 percent of those PCs are ready to run Vista Premium and take full advantage of the software. But it's hard to predict how each individual PC will fare during Vista installation.

"Intel-based Macs sold in the last year will probably be able to run some flavor of Vista, but Apple does not have Vista drivers yet, and they are not supporting it. We just don't know yet," he said.

And if frustrated consumers change their minds, simply returning Vista for a refund is not an option at many retailers. Most typically do not allow consumers to return opened packages when it comes to software. But Vista is unique: because many consumers may not know if their computer is completely Vista-compatible until they try to install it, some retailers are making exceptions.

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