Set Windows 7 Default Login to a Non Domain Account

If you open up the GPO editor

gpedit.msc

you can edit the option under:

administrative templates 
system
logon
assign default domain...

click ENABLE and the enter "." as the domain name. That should default your login screen, after a reboot, to the "computername", which will authenticate your local accounts by default.

You'll of course have to type domainname\domainaccount or a UPN if you need to log in with a domain account.

You can use Group Policy (local or domain) or edit the registry directly.

Direct registry edit seems to work best for us. We use a generic script to assign the local computer name, with the variable %COMPUTERNAME%, as the default domain for logon where needed. Run the following:

reg add HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Policies\System /v DefaultLogonDomain /t REG_SZ /d %COMPUTERNAME% /f

If using GP look under Computer Configuration, Administrative Templates, System, Logon. The setting is labeled "Assign a default domain for logon". However, entering %COMPUTERNAME% here does not appear to be correctly interpolated prior to the logon display.