My advice for hard drives and storage is:
Partition your large physical disk into one smaller Windows-drive, with maybe 50 to 100 GiB, and several game and data stores. In case you have to format Windows, you will have your games on another partition and they will be untouched later on. Steam itself is able to be installed and working from any partition and can nowadays install games to different drives (see its settings for this).
I can only urge you to partition larger drives no matter what. This applies to each and every data. And try not to save pictures and .documents etc. in those Windows folders.