How to reinstall previous Windows Operating System after Windows 7 has been installed
For all those wanting to restore their previous operating system from Windows 7 to the old versions, there is a way. 
Read on for instructions on how to do so…
Steps to take:
- Make sure there’s sufficient space on >Drive C<
- Double click >Drive C< and make sure a folder named >Windows.old< is present
- Make sure >Windows.old< is smaller than the free space available on >Drive C<
- Then place the >Windows 7< DVD and >reboot<.
- At the >Install Windows< window click >Repair Windows<
- At the >System Restore Option< windows, choose your >Windows 7< version to repair and click >Next<
- Then still at the >System Restore Option< windows, click >Command Prompt<.
- In the >cmd< window, type the following commands :
- C:Md Win7
- Move Windows Win7\Windows
- Move “Program Files” “Win7\Program Files”
- Move Users Win7\Users
- Attrib –h –s –r ProgramData
- Move ProgramData Win7\ProgramData
- Rd “Documents and Settings”
9.Then move the files in >Windows.old< by typing the following commands:
- move /y c:\Windows.old\Windows c:\
- move /y “c:\Windows.old\Program Files” c:\
- move /y c:\Windows.old\ProgramData c:\
- move /y c:\Windows.old\Users c:\
- move /y “c:\Windows.old\Documents and Settings” c:\
10.Finally you need to restore the boot sector of the previous OS
11.If your previous OS was Server 2003, XP or 2000 type the following in the command prompt – X:\boot\bootsect /nt52 c:
12.If your previous OS was Vista, type – X:\boot\bootsect /nt60 c:, where X is your DVD drive. Replace with appropriate letter!
13.Exit >command prompt< and restart the PC.
