I just got an Intel Pro 100S Dual Port NIC. Does anyone know how to setup network load balancing in freebsd with this card?

Need more information. Load balancing is a broad concept. Do you want to bond the connections to use the entire bandwidth across both ports? This requirers configuring the switch also. Or are you only looking to balance across outgoing connections? This is in relation to LAN not WAN balancing. Need more specifics.

Chuck