Use cvs.moodle.org as the address of the CVS server. Currently this is an alias pointing to Sourceforge so it's effectively the same as always. The difference is that I can change this alias in future to a new server anytime and you should experience minimal disruption.
Switching CVS servers is very easy on Linux, just run this in the main Moodle directory to edit all your Root files:
find . -type f -name Root -print0 | xargs -0 perl -pi -e 's/@moodle\.cvs\.sourceforge\.net/@cvs\.moodle\.org/'
For Tortoise on Windows do something like http://www.tortoisecvs.org/faq.html#changecvsroot ... ie:
1) Install WinCVS and launch it.
2) Navigate to and select your Moodle folder.
3) Choose 'Macros'
>CVS>Change Root from the menu.
4) Accept (or change) the default for the 'old' server.
5) Type cvs.moodle.org as the new server and click OK!