Authorized Users in Get Info window...


I have 2 accounts on my computer running Tiger 4.1. One is for me and the other for my wife. I just gave my wife access/permissions to my pictures folder because I want to be able to share pictures and when I changed the "groups" field to include her, I had a drop list list of about 20 different names that I do not recognize. Where could these be coming from? There have been no user accounts set up with these strange names. Looks like someone has been trying to access my computer but not sure...Any ideas? Could this be a firewall issue?
No, nothing out of the ordinary. My system shows 24 different users, and 44 groups, in addition to the two accounts that I have set up. These are not indicating unauthorized access, and are the various internal groups naturally setup by OS X, and its unix base. Just choose the user with the name that you know, and ignore the others.
A lot of different Unix applications are separated from each other in order to make sure that something happening in one doesn't affect files belonging to another. To make this possible, they are simply installed under different accounts, and their respective files are then assigned to their parent applications account.

There are also other accounts, that are there for specific use, most of these are accounts that "normal" Mac users never bother with, but they come in handy for experienced Unix users and system administrators.

If you want to learn more about accounts, processes and privileges on your system, I suggest you pick up a book, or read a tutorial on the Internet, about Unix system administration.