Connect the crossover cable directly between the network adapters in the two PCs. Open the Network Connections folder in the first PC, right click the Local Area Connection and select Properties. Highlight the entry for "Internet Protocol (TCP/IP)" and click the Properties button.
Click "Use the following IP address" and enter:
IP address - 192.168.0.1
Subnet Mask - 255.255.255.0
The other entries can be left blank as there is no internet access involved. In the second PC, allocate the IP address 192.168.0.2 with the *same* Subnet Mask of 255.255.255.0
Set any folders that you want to have available over the network as "shared" by right clicking and seleting the Sharing & Security option. Set at least one folder as "shared" in each PC to help getting them communicating.
Normally any firewall software has to be configured to allow access to the networked computers, but if you are not connected to the internet when transferring files, any firewall can be temporarily disabled.