Is the drive you are trying to copy a boot drive? This makes a difference. If it's a boot drive, you will need to clone the drive using something like clonezilla. If it's a storage drive, you can simply do a regular file copy from one drive to the other.
If you have any free sata ports in your computer, just hook the new drive up and start the cloning or copy process. If this is to be a boot drive, be sure to go into the bios after and change the boot drive. Once you are sure the copy process worked for you, then you can format the old drive.