In June, a bizarre rumour circulated on the web. The story alleged that Microsoft was negotiating to acquire Claria, the adware company formerly known as Gator.

Why bizarre? Gator's software is widely detested. Users install it without realising, usually as part of some other software download, and then enter PC hell, bombarded with pop-ups, pop-unders and ad-laden search pages.

Google for "remove Gator", and you are rewarded with over a quarter of a million hits. If Microsoft were to acquire Claria, it would be a PR disaster. It would also be a curious reversal, since Microsoft's anti-spyware tool detects and removes Claria products.

At least it did, and this is where the real story lies. Microsoft recently amended its anti-spyware tool. Claria's software is still detected, but is no longer quarantined by default. Instead, the user is advised to take no action. The same downgrade has been applied to several other products widely considered to be spyware. The obvious conclusion is that Microsoft is no longer serious about protecting its customers from spyware.

The obvious conclusion is wrong. The real problem is that anti-spyware products are vulnerable to litigation. A virus is a virus, but spyware is not so simple. On its web site, Claria complains about "faulty consumer anti-spyware software programs that do not honour basic principles of transparency and informed consumer consent". That is little comfort to spyware victims, but arguable in court.

Claria's speciality is what it calls "behavioural marketing". By monitoring the sites you visit, it sends advertising that matches your interests.

Opinions will differ on whether or not that is desirable, because of its privacy implications, but it is the natural evolution of something like Google's contextual advertising. Like it or loathe it, Claria is offering a service.

It is hard to see how Microsoft or any vendor can create software that purposely disables another company's products unless it has a sure legal footing. And it doesn't. Unfortunately, it is nearly impossible to frame legislation that curbs the excesses of adware and spyware without also interfering with normal computer use.

The sad truth is that anti-spyware software is not enough to protect users. One answer is to think before you click, but nobody deserves to have their computer vandalised or their personal information broadcast because they clicked once on a misleading dialog.

More realistically, the solution is to secure the operating system. I won't beat up Microsoft for its anti-spyware software, which despite the above issues does a good job by monitoring system changes and popping up warning dialogs. The current offering is for home users, but an Enterprise version with management features will follow.

However, I will beat up Microsoft for making Windows XP an operating system that almost insists you have local administrator rights, giving spyware free rein.

At its Tech-Ed conference this month, the firm told us how Longhorn - the next version of Windows - will put everything right, applying the least-privilege concept to both users and applications.

Maybe, but users are currently paying a heavy price for mistakes made back in 2001, when Microsoft released Windows XP.

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