NAT vs. ICS

Hi. I need advice. I just installed Windows Server 2K3 and was about to configure NAT when our senior consultant told me to use ICS instead. Should I follow him or go with my original plan, which is NAT? If I do NAT, would need a 2nd LAN card? The consultant said a single LAN card would do but I think adding a 2nd one is the best way to go. Am I right? I’m not an expert in networks (our expert just quit) so I would appreciate help from you.