you can't use this in the new xbox 4gb slims as the older hd are not not licensed by Microsoft well not if you go on live you can get banned a lot of questions can be answered with google
yes u can use this on a new xbox if u have the right torque bit. i think its a t10. ive done it 2 times for friends that had old xboxs and got a 4gb slim. u take it apart and carefully pop it into where the hard drive goes. or u can buy a plastic case for a couple bucks online and it fits in it. and to ky wildcats. the hard drives in the old 20s is a microsoft hd.