If any of you people, like me, use windows 95 then chances are your port 139 is open, whether you have file sharing enabled or not. Most people say, that because you have no file sharing enabled, well then it doesn't matter that your port 139 is open. Well, why take any chances. There are 2 things I know of that you can do to close that netbios port. One is to download a .vxd file that will close it for you, I believe that it is an update. The other, more simple option is to download a tool from grc.com, it is called NoShare, if you wish to open up port 139 again, you can download the other tool, LetShare.
NoShare can be downloaded at http://grc.com/files/noshare.exe
LetShare can be downloaded at http://grc.com/files/letshare.exe
Secure your comps people.