Deep Rybka 4 UCI is the world champion of chess engines with a rating of 3250+ points ELO. The main developer of the program - international master Vasik Rajlich (Hungary) has inserted the algorithms of positional estimation into it which are as close to the chess-player's style of thinking as possible.
Rybka is a UCI chess engine, which means that you can use it with almost any modern chess user interface such as Aquarium, Chess Assistant, Shredder, Fritz, Arena, Chessbase, ChessPartner, etc.
This version runs on all processors under the Windows operating system, but if you already have or plan to get a multi-core/multi-processor system this is the version that allows you to take full advantage of the hardware, resulting in much faster processing speed and stronger play. If you only need a single core version, look for Rybka 4 UCI.
System requirements: PC, 256 MB RAM, 4GB of free disk space, Windows 7/XP/Vista