Ubuntu Networking :: A LAN Between A Wifi Connected Laptop And A Wired PC?

I have an Ubuntu laptop connected by wifi to a Cisco router and a desktopUbuntu PC conneted by wire to the same router. I would like, if it's possible to connect them without using the Internet (I mean what I want it's not just communicate between them using SSH over the Internet, for instance, but also communicate without connecting to the Internet). My DSL connection it's 4 Mb/s while my router can work up to 100 Mb/s so I would like to take advantage of these 100 Mb/s to transfer files between the two computers instead of using 4 MB/s