Move files from c: to another permanently attached drive (directories such as c:\windows\Installer and c:\windows\winsxs are usually the worst stores of data)
Open command prompt "as an Administrator"Run the following command {replace the curly brackets with the relevant information- example below}:
mklink /D {original location} {new location}
example: mklink /D C:\Windows\Installer D:\C_DRIVE\Windows\Installer