Wireless commonly is used with either ADSL or cable connection to Internet. If he orders that with Netzero, it's quite possible they will offer him the device he needs (a modem-wireless router combination).
Using it with dial-up is possible also, but outdated. http://www.notebookforums.com/thread113829.html tells more about that.
My brother-in-law only has access to dial-up and want to buy a laptop. How can he connect wirelessly to the internet? The laptop will have Windows 7 and he will probably use Netzero as the ISP. There will be no computer, so no network, only the laptop.
Thanks for any help!