If you don't have the money for Fritz, just download the Arena Chess GUI, install and play. It's a great free GUI.
A couple of engines are included, and it's easy to install stronger engines like Houdini and Stockfish if you like.
Mod Note: Please do NOT share serials for programs, nor ask for serials for programs.
Yeah you can do all this free and legal. I have Rybka 4 and sometimes I use stockfish instead.