Deathstroke said:
And going to back to Factory will completely reformat my HD, right? I have my user backed up so no worries.
It will reformat the partition the operating system is on. You can reformat other partitions (if there are any and you want to) from within Windows (as you can now before reinstalling).

If you do a clean install make sure to use the "advanced" drive options at the start of the installation process as that allows you to format the partition first. Its in small print on the screen and not obvious if you are not familiar with it.