If this is a simple SharePoint installation, it will be easier to run hte configuration wizard and create use the option create a new farm. This will create a new configuration db. You can then restore the SharePoint site you have been testing by creating a new web app and attaching the content database from the original web app hosting your sites.
1. run configuation wizard using create a new farm option
2. Once in central admin, create a new web app with a database called delete_me
3. remove database on new app by looking at web app porperties and content databases option
4. find the name of the old content database you used p[rior to changing server name
5. add the old contentdatabase the the newly created web application using the command stsadm -o addcontentdb
5a...use stsadm -help addcontentdatabase to see how to use the command
6. after adding the content database to the new app, restart IIS by using iisreset
7. Browse to all urls and check to see if content is ok
8. restart your search services