In previous versions of Windows the built-in Administrator account was enabled default (this was before Vista). This was a major security risk because hackers knew which they account they needed to attack to get complete access to the computer.

In Vista if you do a clean install (not an upgrade), this account has been disabled by default. If for some reason you need to reactivate this account (which I recommend against unless there is a good reason) the instructions are below:

    * Log on to the machine with a local administrator account (if you don't have one already then these instructions will not work for you).
    * In the Search field under the Start menu type MMC.EXE and press the Enter key. Press Continue button in the UAC prompt to open the console.
    * From the File menu, select "Add/Remove Snap-in".
    * In the "Available Snap-ins" list on the left, scroll down and select "Local Users and Groups", then press the Add button.
    * In the "Choose Target Machine" dialog box, select "Local Computer" press the Finish button, then press the OK button.

    * Expand the "Local Users and Groups" icon in the left pane and click the Users folder.
    * In the right pane, right-click Administrator account and select Properties
    * In the General tab, uncheck "Account is disabled" box, then press the OK button.