Changing base URL setting - what else must I do?

[Spaceman]

^ Can you access the newdomain.com already?

My advice would be to move everything to the new server and change the folder on the old server.
That way your admin access will not get confusing.

Wait till domain propagates and then change the settings.

Also, how are you moving everything, SSH, FTP?

Thanks internet54 for all the advice. Everything is solved now - it's the DNS propogation. And to answer your questions, I was somehow able to access the new hosting server via newclient.com on and off - very weird and which caused me problems. As for moving everything to new server, I probably wasn't clear but I built the new site in the new server. An old site is residing in an old server which I have no control over. When my site was ready, the client pointed his domain to my server.

But all has been ok now and stable for the past couple of hours.

Thanks once again for sharing your knowledge, internet54 - they helped me understand. And to the gang who built GetSimple - I'd call it GetSimplyWonderful.