Question details: One of the laptops doesn't have a wireless card.

Answer:

You need to buy a wireless adapter for the laptop that doesn't have a wireless network card. You can find the best wireless laptops cards on About.com.

To share files you can use WiPeer which not only supports directly file sharing between computers but also playing multi-player games, chatting, and others.

Some of it's major features are:

-Ad-Hoc instant messenger
-Create Ad-Hoc networks
-Interactive Multiplayer Games
-File Sharing&File Searching

More about WiiPeer and a download link can be found here.