Last week, Microsoft announced that it was killing the 'kill switch' built into Windows Vista.

While it has never recognised the term 'kill switch', Microsoft's beefed-up antipiracy software could effectively render a PC running Vista unusable for anything other than paying for a legitimate product key. Microsoft called that "reduced functionality". This autumn, Apple iPhone owners called the practice "bricking". In all cases, users hated the concept and haven't been shy about sharing their opinions.

Someone at Microsoft must have been listening. But because the company's anticounterfeit scheme is both jargon-heavy and inherently confusing, an FAQ seemed like a good idea. Here's the scoop on the modifications.

What changes did Microsoft make?

If you're thinking that Vista's product activation - or its validation and revalidation - are history, think again. Only the results of not activating a copy of Vista and of failing validation have changed, according to Alex Kochis, the senior product manager for Microsoft's Windows Genuine Advantage (WGA) program.

Specifically, Microsoft is ditching what it has called "reduced-functionality mode" and "non-genuine", the states that came into play when users didn't activate their copy within 30 days, activated it with an invalid product key or failed the persistent anticounterfeit validation tests that Vista did on itself from time to time.

In the worst-case scenario - reduced-functionality mode - nothing but Internet Explorer worked, and then only for an hour at a time before the operating system automatically logged off the user.

Non-genuine was more forgiving, but even then certain Vista features were disabled, including the Aero user interface, the ReadyBoost disk-caching tool and some parts of the Windows Defender antimalware protection. Nag notices to get legit were also slapped on the screen.

So what's the new plan?

Rather than dial down the operating system's feature list, Microsoft will instead add to the nagging.

This is what users will see when they migrate to Vista Service Pack 1 (SP1) next year:

- During login, users must wait 15 seconds before clicking the "Activate Later" button in the two-option dialog to proceed to the normal Vista desktop
- A new black background prominently marks a machine as running pirated (or at best, questionable) Vista
- A 'nongenuine' label appears in the lower right-hand corner of the screen
- Every hour, an 'Activate Now' alert pops up

Under what circumstances will users see these?

As before, if users don't activate Vista with a legitimate product key within 30 days, the black screen and nagging reminders begin appearing on day 31, Kochis said.

Actually, the nagging starts way before then. Notices to activate appear daily starting on day 3 of the 30-day grace period, and they continue through day 27. During days 28 and 29, however, the notices show up every four hours. On day 30, they pop up hourly.

The 15-day grace period for copies that have been pre-activated by the reseller also remains unchanged, Kochis said. "This is extremely rare and only appears if the association between that specific computer and the operating system is broken," he said. However, if a users swaps out a reseller's machine's motherboard for one from another vendor, Vista starts a 15-day countdown. An inability to reactivate brings the black screen and nag notices starting on day 16.

Ditto for the infamous three-day grace period if Vista determines that the user has made major changes to the PC which, by its logic, could mean that the operating system has been installed on another machine (when in actuality, the original hardware may have been only upgraded). The usual notices about activating appear during those three days, said Kochis, but on day 4, the new effects kick in.

The changes will also be seen if Vista won't revalidate online, which is required to download some software from Microsoft's site. Vista also periodically revalidates, or tries to, even without any download attempts; that's part of Microsoft's scheme to limit the damage done by the theft or leak of volume licence keys.

"If Vista fails validation online, which is much more deterministic and may be because the [product] key has been blocked, the black screen and notices can start right away," Kochis said.