calvin47,

This thread is 3 years old, and things have changed a lot in that time. However, for possibly the first time, I am inclined to agree with you provided that you take the timeline into consideration, and we will only go back to Windows XP (2001).

If your computer is wide open, random strangers will have found it already and stolen everything worth having.
Not really people, but internet worms such as Blaster and Code Red. In the early days of Windows XP, the firewall was not turned on by default so you would be infected if you didn't activate it or install a better solution. I believe that this was rectified in SP1, where the firewall was turned on by default?

actually telling people won't make any difference.
Only if they can be trusted? otherwise you would be open to a DoS attack, particularly if you have a static IP address.