Although the company will still allow pirated copies to download security updates, in order to prevent viruses from spreading lightning-fast across the Internet.
Microsoft holds 90 percent of the world's operating system market and claims it is losing billions of dollars a year due software pirates.
Customers who discover that they aren't using a genuine product will have two options. They will be able to get a genuine copy of Windows for free if they fill out a counterfeit report identifying the source of the software, providing proof of purchase and returning the counterfeit CD.
The other option is to buy a copy of Windows XP Home Edition for $99 or a copy of Widnows XP Professional Edition for $149. Normally these versions cost respectively $199 and $299. More details at BBC