Yes well IF you use two network cards, a WiFi Adapter & an Ethernet Adapter, you can do this, now with a WiFi adapter, as you say, What you do is connect to the internet on the PC, and "Share" the internet connection via the WiFi. You set up the WiFi as either an "Access Point" or a an "Ad Hoc" network, if you want to communicate with the "Other" PC's, and have then communicate with you, as well as access the Internet. So setup is simple, using the manufacturers DVD install the WiFi. card, then, Set it up as you wish, the PC's that connect should be in the same Workgroup, have sharing enabled and be passworded too then as said connect to the Internet and the "Other" pc's will be able to "Burrow" out through you Internet, through the ADSL Modem attached to the "Main" PC. Usually via the Ethernet port. You still need to set up an SSID and use a WAP/WEP key for security. on the WiFi card.