Wireless connection to internet. I have a Telkom ADSL 5102G modem connected to a Windows XP

Question

I have a Telkom ADSL 5102G modem connected to a Windows XP desktop and had a laptop that connected wireless to the internet.Now I have bought a laptop with Windows Vista that cannot .It sees the network
but says it is unidentified and only connects locally.It then shows that it is a public network,but I go to Customize and change it to Home,but when I try to connect again,it defaults to Public,therefore cannot access internet.