Black ICE Defender & networking

I have a client running a win98SE network of 2 stations, sharing a DSL internet connection through a network hub.
since they are running multi-user apps, the shared printer, and database files reside on one computer.
Black ICE Defender has been installed on both machines.
Why would the machine acting as a pseudo-server get tons of intruder hits, while the other computer is relatively hit-free?
The one getting all the hits gets a lot of NetBIOS hits. Is that related to networking?

Thanksfor the help,

gilles mailhiot