It is always helpful if you post the version(s) of Windows involved in your problem. First, you need to make sure that each computer has a unique IP address. Since there is no router involved, there is no dhcp server, so you will probably have to assign IP addresses in TCP/IP properties. Firewalls are the major cause of lack of connectivity. If you are running Windows XP SP1, you need to disable the XP firewall on the local area connection. If you are running Windows XP SP2, then file and printer sharing must be checked off in the Exceptions list of the Windows Firewall. If you are running a third party firewall, like Zone Alarm, Norton Internet Security, or McAfee Security Center, then you need to read the manual on how to configure the firewall to allow local network access.

Steve

windows (XP) should automatically create a private IP address for you --  if you can only ping one way it's a software firewall in the way...