You can retrieve the 6.2.27 version from http://boincdl.ssl.berkeley.edu/dl/wcg_boinc_6.2.27_windows_intelx86.exe


Changes from the 6.2.25 version:

• When you close the manager, you will be asked if you want to stop the core client as well (even if it is running as a service).
  
• You can control whether you want the BOINC manager to start up automatically via the Advanced View -> Advanced Menu -> Options

Please note that these features will not work with Vista for users that have UAC enabled.

You can read about the changes in 6.2.25 at: http://www.worldcommunitygrid.org/forums/wcg/viewthread?thread=22231