In addition to more obvious changes, Vista includes a number of behind-the-scenes changes. Some are useful, others...not so much.

Microsoft's new anti-piracy measure: SPP

One of the most controversial under-the-hood changes in Vista is its new anti-piracy system, called Software Protection Platform (SPP). In a nutshell, if the system thinks your copy of Vista isn't valid, it sends numerous warnings and gives you a grace period to resolve the problem. At the end of the grace period, your machine goes into reduced functionality mode (RFM), in which everything except your Web browser is disabled. For the full details on what SPP is and how it affects your system, see SPP.

Our take on SPP: Microsoft doesn't really care that some percentage of the people whose Windows installations SPP convicts of being pirated or tampered with might be false positives. Those people have absolutely no recourse but to call Microsoft's WPA support number, and they might not get a sympathetic ear. We all know software is imperfect. Yet Microsoft's policy does not allow for how to handle that imperfection.

A much wider group of people who are stung by SPP may well, in fact, have pirated copies of Windows without having any idea that they do. Three common scenarios include buying Vista from an unscrupulous online retailer, buying it from a small OEM PC maker who is reusing licenses, and bringing your Vista machine to a repair shop that reinstalls Windows Vista with its product ID, not your product ID. Again, there's no leniency to the end user in these scenarios. You may hold a valid product ID for your copy of Windows, but you will need to be able to figure this out on your own. And in most of these scenarios, the product ID you hold may in fact be pirated. You've purchased Vista in good faith -- and Microsoft is going after you, not the person who did the pirating.