The whole point of the backup is so that you don't have to restore using your Windows 7 disk. Doing a backup gives you a way to get right back to where you were at the time you made the backup.
When you say "restore using my Windows 7 disk", I believe you are referring to Restore Points. That is a different type of backup. A restore point restores only Windows, not your data. And it is not a perfect restore like you would get if you did a full backup with a third-party backup program; in other words, it is possible that you can't get back in business with Restore Points.
When you say "restore using my Windows 7 disk", if you mean the Factory Restore disks, you won't be doing a restore of your current Windows install; you will instead be doing a restore of how the computer was new, when it was first pulled out of the box. So it is valuable to have a set of Factory Restore disks as an alternate way of getting back up and running; but not to get back to where you were right before the crash occurred.
Let's say your hard drive crashes, and you need to replace it:
- If you have done a full backup with a third-party backup program, you can install the new hard drive, restore the latest backup, and be right back in business.
- If you restore using the Factory Restore disks, you will be back to square one, in brand new condition; and you will have lost everything you did since that time.
- All of your Windows restore points would be gone and therefore useless, if your hard drive crashes.
If you want to upgrade from a hard drive to an SSD, you can do a backup with a third-party backup program, install the SSD, do a restore to the SSD, and then enable TRIM on the SSD. You will then be up and running in about an hour with an SSD.
If you go with a third party backup program, be sure to create their emergency boot disk for your computer. The emergency boot disk allows you to boot the computer and do a restore if the hard drive is blank (i.e. if Windows is not on it). Without the emergency boot disk, you are dead in the water if your drive crashes.