Virtual Cyber Cafe

I need to create a virtual cyber cafe, that is I need to provide wireless internet access to anonimus computer users with their own hardware (laptop PC or MAC).
My ideal scenario is as follows:
The client sets there network card for automatic addressing
A DHCP server gives them an address
The client then opens a web browser, types in the address of the local Intranet server and buys internet time via paypal from a link on that page

If anyone has any ideas about how I might achieve this I’d love to here them