Since MS Vista the built-in offline files feature is robust and a better alternative to old well known synctoy tool,

The offline files uses a cache directory located under c:\windows\csc

to redirect the c:\windows\csc to another drive (to save space on the system drive) follow this procedure:

  1. Create a folder for your offline file cache. Something like D:\OfflineFiles.
  2. From an elevated command prompt type the following: Takeown /r /f C:\Windows\CSC.
  3. Open the Sync Center and go to Manage Offline Files.
  4. Click Disable Offline Files and restart the machine.
  5. From an elevated command prompt issue the following commands:
    rd /s C:\Windows\CSC
    mklink /J C:\Windows\CSC "D:\OfflineFiles"
    

    (or whatever your folder name is, but be sure to use the quotes if you have space(s) in the name).

  6. Reopen the Manage Offline Files window and Enable Offline Files.
  7. Restart the machine.

All files/folders that are made available offline should now be redirected to whichever folder you specified.