For your lan use direct conncet...or samba (just like the polish suggested)...both protocols can be used on windows and linux, dc also on mac and probably mac does support samba as well.
Edonkey for LAN file sharing : very bad
Direct connect for LAN file sharing : very good
Samba: good
IRC : bad
Advantages of direct connect : no hashing required, on LAN you often tranfer huge amounts of files, that would take really long...and they'll hardly get corrupted. Furthermore on dc++ (works quiet well on wine if you use some native windows dlls) also has corruption-safe tranfering (but it's not like they'd get corrupted on LAN!).
You can join a hub (edit: somebody in the LAN needs to run the hub but it's not any harder than setting up an edonkey server) and even chat/private chat and can kick/ban users and can allow certain users to join, can set share restrictions (to make sure all LAN users really do share something) and there's no such a thing as bandwidth limiting. All tranfers will go fine, just make sure you enable unlimited upload slots. ...and don't use the edonkey damn it, it sucks for lan.
And if you really only have your own computers in the LAN...use samba...
