Now, most people hear the security threats and the claims from the Microsoft and from the Linux camp that their OS(es) are secure. However, most people just feel a little uneasy, not knowing what a "buffer overflow exploit is".
How do you think Mcafee and co make their money
This one is a little more tangible though. Anyone with a Windows 2000 CD can boot up a Windows XP box (PC) and start the Windows 2000 Recovery Console (option "R"), to troubleshoot problems and hopefully find a way back to normality.
Windows XP then allows the visitor to operate as Administrator without a password, even if the Administrator account has a strong* password.
The "administrator" can access all user accounts that may be present on the XP machine, even if those accounts have passwords.
It is even possible to copy files from the hard disk to a floppy disk or other removable media - even an Administrator is normally prevented from doing when using the Recovery Console.
*
Strong means a pass word that is hard to crack, long and with a mixture of numbers and alphabetic characters for example.