I have hosted a website. But now my client asks to change it to http://sites.google.com. They have registered their domain with Google.
I logged in the site and saw
You should consider hosting your solution using Google's App Engine instead of Google Sites. You can set it up so it uses PHP (see link below), you can configure it to use your domain name and you get enough CPU, disk and bandwidth allowance to serve around five million page views for free each month, if you are serving more than that, their prices are extremely competitive.
Google App Engine: http://code.google.com/appengine/docs/whatisgoogleappengine.html How to setup PHP using Google App Engine: http://blog.caucho.com/?p=187