Eddie, I use a CTX[1998 model] Pentium2, 200mmx, with a 12 gig hard drive,, it has a built in midi port[so I don't need a midi interface]. Winamp for playing MP3's and VanBasco to play Standard Midi files..If you are going to look for a used model I would recommend a Pentiun2 or higher with a 400 minium speed[not that a lower speed is not okay for playbacks], necessary for the newer audio/recording/edit software..