LAN messenger software - HELP!

Our company is in need of an instant messenger system that is cross-platform friendly. The system needs to work for OS X 10.3 and up, and also Windows 2000 and XP.

Something similar to this: outlookmessenger.com
Outlook Messenger doesn't work with OS X 10.3

I can't seem to find anything that meets our OS needs. Any ideas?

What protocols does it need to conform to? Adium is a multi-protocol IM client. Is that what you're looking for?

Microsoft has a version of Messenger for OS X too... what are you running on your Windows machines?

I imagine you're looking for a messenger that doesn't communicate OUTSIDE the LAN, correct? Just secure, internal communication?

If so, check out the website called macpopup.com. I found it using a google search for "cross platform LAN messaging".

I haven't installed to test it, but from the descriptions on the page, it appears to be just what you're looking for.