The 3 card plugins all get installed to the same partition of the hard drive, but just a very very small amount (no more than 200MB), not the entire partition gets used by them.
You don't need to format the drive. However, keep a fresh set of cdr backups of your plugins, just in case something ever does go wrong with the hard drive.
Installing plugins won't do anything to the hard drive.
Regardless of plugins, regardless of hard drive running good or bad, always keep your work backed up - all of it! Losing work is heartbreaking.