You can customize the 'Default User' profile by:
Creating a new user with local admin rights.
Login as the new user and make the changes you require such as
- Desktop Wallpaper
- Desktop Theme Keyboard language
- Screen Saver
- Power Saving settings (this needs admin rights)
- Start Menu
- Desktop Icons Program Shortcuts
Once you have finished remove the admin rights from the user (unless you want the default user to have admin rights), and reboot the machine.
Log back in as a different user with admin rights, open My Computer, Tools Menu, Folder Options, View Tab and make sure 'Show hidden files and folders' is enabled. Click OK.
Next, right click my computer and choose properties, click the Advanced tab, and then the settings button for user profiles. Highlight the new user you created earlier and click the 'copy to' button, click browse and expand the tree to c:\documents and settings\default so default is highlited.Click Ok. Click the 'Change' button below 'Permitted to use' and type 'everyone' and click OK. Back on the 'Copy to' window click OK. Click Yes on the confirm copy dialogue.
If the 'Copy to' button is greyed out make sure you have rebooted before copying the profile.
Now when you login as a newly created user the customized default profile will be applied.
Later on you can turn this into a Domain default profile which would be applied to any domain users logging onto any Domain joined computer. Add in some Group Policy to deploy applications / map drives/ printers /etc and adding new user in the future will just take a few seconds.