Fundamentally, sslstrip acts as a transparent proxy for web traffic that changes https:// to http://. The transparent proxy functionality is implemented using ARP spoofing, which means the network switch needs to be susceptible to ARP spoofing attempts.
So you'd install sslstrip on pc1, make sure pc1 is able to forward packets, start arpspoof (separate package than sslstrip - i think arpspoof is on SF), and run sslstrip. You can see if arpspoof is running by running tcpdump on pc1 or checking the mac address table on the broadband router - the internet router should list the MAC address of pc1 and tcpdump should show all packets routing from pc2.
Aside from that, moxie's defcon prezo is published here. There's also videos that show you how to make this work link