Local Windows users won't receive my message via Messages.

Hi, I have local network with some Mac and a couple of Windows users. I have installed Bonjure on all PCs and Pidgin messanger inorder to be able to coumunicate, via Messages between Mac machines and Windows. But I have run into an annoying problem. Mac users can send and recive messages to eachother, they can also see eachother on the network, they can see Windows users too, but they can't send messages to Windows users, unless Windows users start a conversation with them by sending a message. Windows users can see eachother and other Mac users and they can send messages flawlessly. I tired to turn off all the firewalls to figure out what is causing the problem, but I haven't succeded in resolving the issue. All machines are connectd to an Airport.