Actually, you don't really need the UDF Volume access if you *don't* have a DVD drive. I've got system 8.1 with no DVD and its not enabled for me. The rest of them you should keep. It does sound like you've got a newer computer, or else you wouldn't have the CD/DVD driver extension. Also, unless you are playing 3d games, you can turn off the QuickDraw3D stuff. However, these do provide accelleration for 3d games, so if you regularly use them, keep the extensions on. Like wlonh said, you can turn off all those Input Sprocket extensions, except for InputSprocket Keyboard and InputSprocket Mouse, unless you do have something like a Gravis stick. The OpenGL stuff can be turned off as well without problem, unless you want to play many of the newer PC game ports.