|Yes. It's called Internet connection sharing. It would mean however that your machine would have to be turned on whenever your Father wanted to use the net. Not very convenient and it would also mean both you and your Father would be using your wireless bandwidth and it may slow you both down. It will also depend on whether the LAN cable is a Patch (straight) or Crossover type. You need crossover to connect two PCs. Patch is used to connect PC to Router but most modern routers have self-adjusting ports that can operate with either cable.|
The problem with windows ICS is it assigns IP 192.168.0.1 to the NIC in the host PC and cannot use any other IP. You would then have to manually configure the IP address in your Father's machine since it would no longer have access to the DHCP server in your router. Assign say 192.168.0.2 to his machine and set 192.168.0.1 as gateway.
What IP range is your router using? You may run into an IP conflict and that's another issue to deal with.
ICS is not the only software solution. There are third-party proxy server programs you can install on your PC but for a single client setup not worth the effort.
My recommendation is to spend the money and get him a wireless NIC.
Goin' Fishin' (Some day)