How can I share a PC printer in home network connected with ethernet hub? On the server machine (machine that has printer attached), I can mark the printer as shared. But on the client machine I can't open this machine in network neighborhood (can see it but not open the node). I wonder if the software firewall blocked certain ports. What ports do I need to leave open to achieve this? Do I also need to "logon" from the client machine to the server machine?

You should be able to configure your software firewall for "trusted" computers. Since I don't know what firewall you're running, you'll need to look for something like trusted zones or computers. Then you'll need to enter which ones to trust. In general, with a D-Link router you'll need to enter 192.168.0.100-192.168.0.200 or with Linksys 192.168.1.100-192.168.1.200.