If you want to move a MOSS 2007 databases over to a new DB server, do the following:
1. Run SharePoint configuration wizard (on the web server)
2. Disconnect from existing configuration database (on web server)
3. Move the SITE database over to the new database server (on DB server)
4. Run configuration wizard again and create a new farm (on web server)
5. Give NEW database server and NEW configuration database (on web server)
6. After configuration wizard is finished, create web application by going in the SharePoint Cetral Admin (on web server)
7. Give it any web site name. Here you'll specify the New database server and OLD SITE db name. Hit OK. That's it. So only the combination of New DB server and Old Database name are important to specify in all this scenario.
Now open web browser and open the site with same URL that it had been running before.
You can also follow other processes like descriped on "Ron Grzywacz's Blog"