For machines in the domain, you can modify the Registry to set Automatic Logon for a domain account.
Step 1: Run-> regedit
Step 2: HKEY_LOCAL_MACHINE/software/Microsoft/Windows NT/CurrentVersion/Winlogon
Step 3: Double-click DefaultUserName and enter the username of the default Logon account. If the key value is not changed, create it (string value)
Step 4: Double-click defaultpassword and enter the password of the default Logon account. If this key value is not found, create it (string value)
Step 5: Double-click AutoAdminLogon and set the value to 1. If this key value does not exist, create it (string value)
Step 6: Delete the autologoncount key.
Note: For Vista and win7 operating systems, DefaultUserName must be added to the domain name, or the defaultdomainname must be created without the domain name to set the key value.
Close Registry Editor and restart.
A tool that automatically sets autologon: http://technet.microsoft.com/en-US/sysinternals/bb963905.aspx