You can retrieve the 6.2.28 version from
http://boincdl.ssl.berkeley.edu/dl/wcg_boinc_6.2.28_windows_intelx86.exeChanges from the 6.2.27 version:
- The installer will not install the software as a service by default.
The issues with the UAC controls were still substantial. As a result, we have decided to have the installer install the software similar to how it is installed with the 5.10.45 client. We will continue to work with the BOINC developers so that the needed improvements are in place with the 6.4 client.
You can read about the changes in 6.2.27 at:
http://www.worldcommunitygrid.org/forums/wcg/viewthread?thread=22336