ADSL hardware router probs w/file sharing

Hi guys

i have a 4 port ADSL modem, where i have 2 PCs accessing the internet directly, but i cant get them to share files! can you share files with a ADSL hardware router? if so what special settings do i need, or should i put a second network card in one of the machines and network and ICS? Im running 2x windows XP pro machines (not the FCKGW hack version), its a clients computer, i know how to network and setup ICS but have never dealt with new hardware routers in regards to file sharing

thanks guys

Steve.