First connect both PC's with the cross over cable. From there, go to Network and Sharing Center. In there you should have an icon with the details "Unidentified Network"; open that up (double click). Now, you should see an option that reads "Turn on network discovery and file sharing". If it's disabled, enable it.
If it asks whether you want the network to be public or private, select private. This is because sharing for a public network is disabled by default. You should now have a computer icon displayed in the Network section and can select to view resources, etc.
If the other PC doesn't show though, you might have to join the same workgroup. To do this, follow this tutorial.