format everything and re install. its not that much job really once u have done it a few times. i do this altealst once a year now as i use it for both gaming, music, internetsurfing, mediacenter, torrenting movies etc etc. i use it for everything so i assume it will collect a good amount if shit during one year, so i just format everything sometimes. eventho its not slow i do it, eveything just feels fresh and u start making better and faster backup-routines too.