Best approach to network (connect) multiple home computers

There are 2 desk top computers each having large amounts of stored data on their hard drives.  The 2 computers are about 6 feet apart so they could be connected directly to each other.  One computer is an HP p2-1394 and the other an HP Z210-Workstation.  Is there a simple method to be able to network the 2 computers so that the file folders show up on both folder hierarchies?  I tried to do this but the Norton security firewall didn't allow it.  I'd like to maintain the level of protection on both computers as it is currently and just be able to share data from one to the other.  Thank you.