Secondly, Kopete Jabber uses a library called QCA for encrypted connections as used by jabber. Kopete has an internal copy of this library but your distribution may have separated it out.
If so, make sure you have QCA installed. (Yast-install QCA package). This may be called “libqca1-tls”. Information on QCA for various distributions: KDE Wiki : Google Talk support
Finally, you may need to restart Kopete to get the connection to work if you are editing an existing account.
Note though that one thing has changed since the webpage above was created (all the rest remain the same):
The webpage above states you should check the “Use legacy SSL encryption” checkbox; I found that with this checkbox checked, I couldn’t login to Google Hangouts. Leaving this box unchecked solved the problem.
So, now I have Google Talk (OK, Google Hangouts) messaging on my dear old Pentium 3! Lovely.