If you are having trouble logging on as the built-in Administrator account under 5308, you will need to make some registry modifications to display the Administrator account.

1. Log in using the account you created during the Windows Vista setup process.
2. From the Start menu, click All Programs and then expand Accessories.
3. Right click on “Command Prompt” and click “Run as Administrator”.
4. Click on “Allow” from the Windows Security dialog.
5. In the Command Prompt window, type “regedit” (without the quotes) and press Enter.
6. In the Registry Editor, browse to HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon
7. Add a new key called “SpecialAccounts” (without the quotes).
8. In the “SpecialAccounts” key you just made, create a sub-key called “UserList” (without the quotes)
9. Make sure you are navigated to HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon\SpecialAccounts\UserList
10. In the “UserList” key, create a new DWORD (32-bit) item and name it Administrator.
11. Double click on the new DWORD item and set its value to 1.
12. Close Registry Editor and the Command Prompt.

I'll export my key later and upload it.

PS: I would password protect the Built in Admin account.