Not sure why the other post told you that you couldn't do it and then proceeded to tell you how to do it. I've done this on 5 different machines. It's easy. Acronis has always worked well for me in cloning disks. Please note that if your old hard drive has 200GB worth of data, you won't magically get all of that on a 120GB drive. So you may need to separate data (e.g., music and movies) from the rest and then clone.
thanks. mine is only 60gb. mainly using for os and some programs. so size wise will be more than adequate.