I used to play comp chess when I was young but lost interest when I
discovered computers (and girls :) I'm still an OK player but frankly I was
thrashed by one of the programs listed in our Best Free Computer Chess
review. The way I see it , there's no need for anybody to pay for a computer
chess program when these free ones are so good. And be aware that some of
these free programs can not only play chess but teach you how to play or
provide tuition how to improve your game.
http://www.techsupportalert.com/content/free-computer-chess-and-go-stub-only.htm