The security of any Windows Vista system is only as good as the security associated with its user accounts and logon settings. Keep the following points in mind when it comes to maximizing the security of your system:
Each user should have a personal user account.
Every user account should have a password configured.
A user's everyday user account should always be of the Standard type.
Only trusted users should be granted access to an Administrator account. Even with this access, this account should not be used for everyday tasks.
User accounts that are no longer needed should be deleted.
Use the Run As Administrator feature of the User Account Control to perform administrative tasks when required.