If you have an ADSL Line you need an ADSL modem or router (most of them have WIFI included and should work out of the box.
If you are looking into Zeroshell then there are 2 options
1. You already have it installed and you only need inside an large enough IP pool or dhcp and a wireless access point
2. You are new to zeroshell and would like to use it. Then i am not sure that with your 2 PC’s it is worth all the trouble. YOu need to dedicate 1 machine at least partially to zershell you need 2 network cards and/or vmware. Again the PC’s would connect through an access point or wifi router to the network