Please I need to know this.I am a worker of a company with network of 200 pcs.can IT people see my googletalk chat messages?

If they have the software, they can. Is online chatting against your company policy? Many companies monitor their employee's internet activities. If you are not being productive for the company, you are stealing company time and resources (by using the computer for non company activities).

It's quite simple and straightforward.
Most internet monitoring software can also track IM as a matter of course.

If you are doing something wrong -- on the internet -- on company time

You could be a couple mouse clicks from being terminated --

Big brother is watching you

They sure can and will see what you are doing. I would suggest that you do all your "chatting" at home where you won't have to worry about who sees what. Better stop now while you are ahead. Yes, the IM chat does not go away on the server. Any of your keystrokes are there for all the company snoops to find and they will find.