To bypass log on screen in Microsoft Windows 2008 R2, run the following .reg file:
Windows Registry Editor Version 5.00
[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon]
"AutoAdminLogon"="1"
"DefaultUserName"="YourUserName"
"DefaultPassword"="YourPassword"
You must change YourUserName to your desired user name, and YourPassword to corresponding password.
To import .reg file use:
regedit.exe /s filename.reg
This will import registry values without confirm dialog box. More on importing .reg.
Source taken and more options / registry values: Automatic Logon from windowsnetworking.com
Tested on Microsoft Windows 2008 R2 (Datacenter and Webserver editions).