Indeed, it does happen but its quite rare these days that you'll get individual machine IP, which means working with ISP. Generally thats easier if its a college/uni/business doing their own IT and more difficult if its a big ISP.

yeah, ive found this out.
So by tracking the IPs (and i have), am i right in thinking, it only disclosing info about their ISP and not the PC itself?

Standard WHOIS will tell you ownership of the netblock and who to contact regarding abuse. Problem then is its in someone elses hands to do something, biggest problem is with home user ISPs who tend to be big and faceless. Also ensure that you have the right information, if IP is in an email or something then it could be spoofed in which case you can't do much from the information which you have.

Also note that the computer doing this may be infected by a virus itself, and there might not be an individual involved.

IF you do a lookup on the IP there will be an Abuse email address , mail that and te ISP will take action against the user.

I used to have a few contacts through europe, one guy who did something abit dodge, myself and a guy from norway had his ip, the guy from norway phoned up the company where he used to work, got them to transfer his call to the ISP of the blokes ip and got him cut off immediately

on a slightly different note.
If i was able to determine the IP of a spammer (from the whois lookup - if possible), and the spammer is also sending out viruses, whats the likely hood of me sending that ISP an email and gettting them banned or removed?

I presume ISPs look down on their spammers?

Depends on ISP mate, some people have their own IP records, whats the ip? :look:

if i wanted to determine as much info about an IP as possible, how would i go about it?

im not sure what details i could find, just ISP and location?