Rpg Maker XP, abbreviated as RMXP, is by far the most popular RPG fangame development software available at this moment. It costs $60, a little bit expensive for some aspiring game developers but should be a good deal if you are indeed interested in this. It uses a gaming system called RGSS(Ruby games scripting system), thus you must learn a little bit Ruby in order to program in RMXP(like I did three years ago). RMXP is mostly known for its convenience to create maps and events, which significantly reduces the amount of time to program. Anyone interested? Visit RMXP's official site and see if you will get it for your PC. Note compatibility with Vista may be an issue.
http://www.rpgmakerweb.com/
