This is far simpler than you may imaging, but first can you explain your problem in more detail. What exactly are you trying to do and why? The fact that your HDD has 3 partitions is not, as such, a problem, and installing a new hard disk is not a problem. However, if you want to remove you old hard disk and replace it with a new one, you will need to copy the data from the old to the new. Idelaly a partition manager can do this for you, but you will need to have both HDDs installed at the same time to do this. Let us have more informaiton and we'll advise you what to do.