Journy:

I had a software firewall installed, (Norton), and I also had three PC's on a LAN. I had trouble getting my computers to connect to my shared drives on my PC with Norton. later I realized that I didn't have my computers in the trusted zone. Needless to say, I couldn't connect to it, I couldn't even ping that computer. I think that you should be pretty safe if you put up a firewall, and only allow local access to your shares.