Barry - The 4-port switch allows you to expand your single LAN port to 4 LAN ports. This way, your brother-in-law can plug his PC right into one of the ports and be on his way.

I bought a Linksys SRX Wireless Router a few weeks ago and it has both wireless (SRX200) and 4-port switch. I have a PowerMac G5 and a Dell 4700 at home. The Mac is connected to the Linksys via wireless Extreme Airport and the Dell 4700 is connected via the Gigabit LAN (wired) or Linksys Wireless USB card. Both can see/share each other's hard drive and an HP printer, and can connect to the Internet without any problems.