I have a home network, sharing a printer with my iMac & a PC. I would like to share files between the 2 computers. I can "see" the PC from my Mac, but can't "connect" to it. If I can print from both computers to the same printer and can see the other computer, what do I need to "connect" them in order to share files? Is this an inherent thing, or did I need a 3rd party app?