Administrator account exists on all computers running Windows 2000 Server, Windows 2000 Professional, Windows XP...
Professional and the Windows Server 2003 family. You should occasionally rename this account to make it difficult for unauthorized users to guess this privileged user name and password combination.
To rename the administrator account do the following:
1. Start -> Administrative Tools -> Local Security Policy.
2. Go to Security Options folder and select "Accounts: Rename Administrator Account" policy from available policies.
3. Change to whatever name you want it to be and enjoy a more secure Windows system.