Star wars the old republic is an MMO developed by Bioware. SW:TOR is set further ahead in the starwars canon than Knights of the old republic. You can play as the Republic or as the Empire. With each character that you make you can be either light side or dark side regardless of whether you are Republic or Empire. SW:TOR will become a free to play MMO very soon, hopefully within 2012.

Star Wars: Knights of the Old Republic (KotOR) is a single player, role-playing video which was developed by BioWare and later published by LucasArts. It was released for Xbox on the 15th of July 2003, it was later released for Microsoft Windows on November the 19th 2003 and on September 7th 2004 for it was finally released Mac OS X. The Xbox version is playable on Xbox 360.