if your worried about it, open a dos prompt by typing "command in the "run" box. then you can find out who it is by typing ping -a <ipadderss> at the prompt.
you can also go here and download the zone alarm tool. when you open it you can click on the whois button and it will try to do a search for you. This program was created by one of our own members, Simon Templer. It works pretty good.