ECM Tools:
Download PakkISO 0.4 (Recommended) - PakkISO is *even better* than ECM tools because it automates everything. Download and install, and then simply right click on the game folder and select "Unpack ISO" or drag and drop the game's folder onto unpakkIso.exe. The program will automate all the steps for you. It will unECM the files and decompress the APE files too, to give you a .BIN which you can then mount and play!
OR
Download ECM Tools - Required if your file is of .ECM type and you need to convert to ISO/BIN/CUE. ECM is a special compression technique which allows better compression on CD images and thus saves on space as well as bandwidth!
Learn more here.