It made some games unplayable on my friend's pc. Luckily no important documents lost.
I don't hesitate when deleting games as long as the save data is still there, most games gives warning whether to keep or delete it when installing so I always have space for anything else.
Forgot to tell you guys I'm away to the countryside this week until next Tuesday. Have to walk to net cafe 4 miles just to post this, lol.