Microsoft are so keen to fight piracy - particularly in the Far East and Eastern Europe - that they would rather give away copies of Windows XP to people who may have bought a pirate copy under false pretences than have them continue using it.
"Our goal is not to prosecute the individual; our goal is to get to the source." - Alex Hilton, Microsoft's license compliance manager.
Microsoft is therefore offering anyone who thinks that their copy of XP is not legit to have it checked out by Microsoft and replaced. The deal only covers Windows XP, and only five copies per person can be exchanged, but Microsoft does promise that all copies found to be genuine pirates will be swapped. Sometimes, the copy process used is so good that even a seemingly genuine copy of XP can be a fake.
"Some examples we're seeing from the Far East and Eastern Europe...are very high quality."
What does Microsoft get out of this, apart from the satisfaction of knowing that there are less pirated copies of XP being used? Well, they get a better idea of the extent of piracy globally, as well as making legitimate contact with new customers, who will likely go on to buy legal copies of future Microsoft software. So, as always, you do not get something for nothing.