Sounds like the are connected OK, so pinging would just be a formality, really. Just opne a run box form the start menu and type ping IPaddress where IP address is the IP address of the other PC. If you are not sure of the IP address, open a command prompt and type ipconfig and it will be listed.
Oh, and they both need to have IP's in the same range (eg 192.168.0.x) - the first three sets of numbers should be identical.
i still think it may be a simple file sharing issue - make sure both have it either on or off as per the link I gave above.
Cheers
Mick
Cheers
Mick