Especially when you want to upgrade to a faster, but often smaller, SSD hard drive, you need a way to quickly copy everything on your existing hard drive to the newer hard drive. One of my favourite disk copying tools is Clonezilla, but it isn't good with copying to a smaller capacity drive. You need a tool which can manage the change of partition sizes at the same time as copying the data. A new free tool I found which will do this is called Backupper Standard by AOMEI Technology.
Backupper Standard includes a Cloning tool which allows copying an entire hard drive to a smaller capacity hard drive. Their website has more information about this feature and how it works here and here. (I think the cloning used to be part of a separate free tool, but now it has been incorporated into Backupper Standard. They also have another free tool especially for Windows 8.1, Windows 8 and Windows 7, but I haven't used this yet. It is called AOMEI Backupper Standard For Win7.)
By the way, obviously you cannot clone a larger hard drive to a smaller one if there is too much data on the larger hard drive, too much to fit on the smaller one. You will need to cull out some stuff first!