You can download and install Open Office from http://www.openoffice.org. It is a free open source alternative to Office products but has the ability to both open Office files and save in .doc and .xls formats. It will also open older Office files- which Office sometimes cannot.
Unfortunately, I do not use Windows- I'm a Mac user. But I can tell you that openly posting a product key is against the law and Microsoft is cracking down hard on those who do. I believe that the fine has gone to $10,000 for each instance. And most people don't want to get caught up in anything like that.
Consider Open Office. It will give you the functionality you need without the fear of reprisal.