Download chess playing software and play chess with a computer!
Free Chess Playing Software Programs
listed at en.wikipedia.org/wiki/Chess_engine
Commercial Chess Playing Software Programs
Chessbase: Fritz, Junior, Shredder, Zap!Chess, Chess Tiger, Chesster: www.chessbase.com
Chessmaster by Ubisoft
Lokasoft: Chess Partner, Ktulu, SmarThink, Gandalf, Ruffian, Deep Sjeng, Rebel: www.lokasoft.nl
Rybka: rybkachess.com
Chess Genius: www.chessgenius.com
Hiarcs: www.hiarcs.com