I have installed Boinc 4.05 joining ClimatePredition.
I can not join Seti because server requires version 3 of Boinc.
I assume there is some migration strategy.
I am guessing I should not run versions 3 and 4 of
Boinc on the same machine.
Does version 4 have some compatibility mode to be able to talk to version 3 servers?

Thanks in advance if you can point me to the solution.

Heres the error.

http://setiathome.berkeley.edu/ - 2004-08-29 01:32:25 - Sending request to scheduler: http://setiboinc.ssl.berkeley.edu/sah_cgi/cgi
http://setiathome.berkeley.edu/ - 2004-08-29 01:33:03 - Scheduler RPC to http://setiboinc.ssl.berkeley.edu/sah_cgi/cgi succeeded
SETI@home - 2004-08-29 01:33:03 - Message from server: To participate in this project, you must use major version 3 of the BOINC core client. Your core client is major version 4.
SETI@home - 2004-08-29 01:33:10 - Resetting project
SETI@home - 2004-08-29 01:33:10 - Detaching from project

Never mind..

Found all my answers on the one of the ClimatePrediction forums.