As you know, Windows 7/Vista put all system data and user data on the same partition, normally it’s drive C.
Under this condition we must backup our user data every time we re-install our Windows 7/Vista. From Windows Vista, Microsoft supply us a tool mklink which can create a symbolic link under Windows 7 or Vista just as the command ln under unix/linux. Below is an example about how to put user data on non-system using mklink in Windows 7.
- Enable administrator account and set a password for it.
- Logoff and login with administrator account. Relocate your user data to other non-system partion, for example from C:\users\J to D:\users\J
- Use mklink to create a symbolic link from C:\users\J to D:\users\J: mklink /D C:\Users\J D:\users\J
- Re-login use your own account,you will find nothing changed, but in fact your physical user data is on drive D.
Done. The next time you re-install your OS, just use the same user name, remove C:\users\J then run the command of step 3 again then your user data is back.
Source: http://www.windows7home.net/how-to-move-user-data-folder-to-non-system-partition-in-windows-7vista/
