The new version of BOINC, v5.2.2 is now the official recommended version for Windows. You can get it here:
http://boinc.berkeley.edu/download.php

New Features
- Dial-up support has now been enhanced to support service installs, and shared user installs.
- Account Management has been enhanced and support has been enabled in the stock install of BOINC.
- Alerts have been enabled to provide instant feedback when certain types of errors occur.
- BOINC Manager now supports the Microsoft Active Accessibility standard.
- BOINC is now capable of using HTTPS and has better proxy support through the use of curl.
- BOINC can now use username and passwords for authentication instead of an authenticator.
- BOINC now employs a wizard during an attach to project operation to guide people thruogh the process of attaching to a project as well as check for things like proxy configuration issues.
- BOINC now automatically generates a password that is used for network communication. If you use programs like BOINCView or any other third party tool you may need to look up or change the password specified in gui_rpc_auth.cfg. This change keeps people from randomly detaching from projects over the network on remote machines.



EDIT:
I myself will wait a little more until installing it. Several projects still need to upgrade their serverside software to support this new client.