Sincere thanks for your offer but I will stay with 6.2.14 for the time being for the following reasons:
1. I think it's not bad that I stay with 6.2.14 as long as it is the "official" level for Ubuntu (for support reasons).
2. If I upgraded it would be for the current official level in WCG, i.e. 6.2.15, and there is not much difference between both.
3. I wish to keep Boinc installed as a service as it is now, and I am not too sure it is so "dead easy" to upgrade it manually in this setup?

Thanks again. Jean.

ASSUMING YOU ARE USING UBUNTU Linux

Directions to upgrade to 6.4.5

If it bothers you, let your work cache run down to nothing.
OR
set the client to not receive any new work, set the activity to not use the network at all and then reset it.

Uninstall all BOINC packages using Synaptic

Download the latest RECOMMENDED package directly from BOINC to suit your operating system (Win/Mac/Linux and 32/64bit)

Save the downloaded file in your home folder ( /home/<your username> ) and run it (double click and select "run" if it asks you)

You now have a folder named "BOINC" in your home folder. Open that and double click on the file "run_manager". Click "run" when it asks you. The client set up procedure is the same as you should expect. Leave it open for now. While that is downloading work go through (from your top menu bar on your desktop, NOT in the BOINC manager) <System> <Preferences> <Sessions> <Add> and enter the path to the "run_client" script in the BOINC folder (you can click <Browse> and navigate there if you wish). Enter ALL the details. Click <Ok>. Now when you log in the client starts automatically as a service.

Why go through this? Because Ubuntu NEVER updates the BOINC package for each release. If you want to stay up to date you either have to upgrade your whole operating system, "lump it" or do it this way.

TO UPDATE:

Download the new install file for your archtecture (32/64bit) and open it on your desktop. Open the folder it creates and copy the binary files (boinc, boinc_cmd (or boinccmd), boincmgr, libcudart.so and crt-bundle.crt) to your BOINC directory in your /home folder. Now restart the client (just reboot) and you're running the new version. Use the same procedure to DOWNgrade if you find a new version is screwy or just don't like it.
NOTE: Using this update method (not the reinstall above) you don't need to reset your client or empty your cache but it is a good idea to restart before opening the new manager version, just to be sure.