Can a boss at work read yahoo messenger/msn messenger messages if networked on same server?

If all computers in the office share a server and are networked together, can someone read your msn or yahoo messenger messages you send to someone else? And, is there a way to tell if they have it set up so they can read them?

On both messengers, I have "Save copy of message to file?" left it blank, so I wonder if that prevents them from staying on the server or not.

Thanks!

I'm not asking if they CAN ethically do it, I'm asking if it can be DONE. I know when using a company computer, you have no right to privacy, and I'm not saying anything I wouldn't say to someone at work, but I'm getting the sneaking feeling that after we type a message, a couple of days later management mentions that exact topic.

Just to clear things up... If you are on a network at work, then the network administrator can access and see EVERY SINGLE keystroke you make from your computer.

That means YES they can see you're typing.

Whether it be on messenger, or msn, or EVERY web site you visit, or every key stroke you make... They can read it all.

Only if he/she has your address and password.
if you think he/she has them then change your
p/word.
to do that go to your account and near the top
click on edit pass word then put you original p/word in and then your new p/word in 2 times. for your reminder for your p/word make it as difficult as possible.and thats it
c yah.

there are many programs that allow administrators to watch what goes on in company PC's .. from watching your actual desktop as you type .. to getting any password typed on the machine .. don't read your personal mail on a company pc