Newbie needs NT/Mac/Irix advice

I’m really new at this and could use some sound advice… somehow I wound up in charge of a small network made up of an NT server, 15 Windows 95/98 machines,25 Mac’s, and 1 Irix box. There are lot’s of challenges… mostly between the NT server and the Irix box. Anyone have any suggestions on how to get all 3 talking to each other?