As far as I know, servers do collect such information. Some
simple JavaScript can be made, embedded as part the HTML codes and
your information will be logged. I've done that to keep track of
users. Not too sure if it works for P2P, but if download directly
off websites, the JavaScript works. That's how they check.
I know that for modem and wireless cards, that unique information
will be transmitted no matter what. Not too sure about the hard
disk though. It can be collected, but find it quite useless. OS
wise, it's part of the server's job to do so, whether you like it
or not.
P2P I don't know. I don't use it.
