So you actually have 3 hdds, with each running a different OS, and not a partitioned hdd? You should be able to refresh Windows 8 without losing all of your files, you might want to give that a go to start:
"1. Swipe in from the right edge of the screen, tap Settings, and then tap Change PC settings.
(If you're using a mouse, point to the upper-right corner of the screen, move the mouse pointer down, click Settings, and then click Change PC settings.)
2. Tap or click Update and recovery, and then tap or click Recovery.
3. Under Refresh your PC without affecting your files, tap or click Get started.
4. Follow the instructions on the screen."