Network Problem

Okay so i have a Mac Pro and a Mini in my office..the mini is wired to the pro to give it internet over its wireless because the mac pro doesn't have a wireless card, no problem there. Now another mini in another room is used as a movie/file server with a ton of external drives hooked up. My question is how do i get the mac pro and file server mini to see each other short of buying a wireless card for the pro.