So here is the issue. I was running Windows 7 Home Premium edition. It crashed a week back. It dint work at all. It just showed the black screen with a cursor at bootup. So i had to use my pen drive to install the OS again. But the thing is when i installed it, all the previous files got stored in windows.old folder in the hard drive. I took backup of all the files. So should i delete that folder from the hard drive? And if i do does it mean I have only one OS in my system? Please help me with the same. Thanks in advance.