Browsing for computers for w.less Router

I have MAC G4 with MAC OX 10 and above, 3 laptops which are on the wireless router, and the wirless router is connected to the coperate lan over the wan link.before we had windows xp laptops on the wireless from which we used to acess the coperate computers using the computers ip address, pull files. I am confused how to browse from the MAC PC to the coperate lan netwrk.