In Windows Server 2003, for the first time, you can disable the Administrator account.  My point is that every hacker knows that Windows has a username called Administrator, so defend it by disabling the account. (Right Click the Administrator, Disable)  Obviously you must create another account with administrative privileges.

There are two variations of this tip:

1. You could disable the account from logging on across the network.

2. You could rename the account and create a dummy administrator to confuse would be hackers.