Setting up Vista as WAP (with Ralink)

Trying to set up Internet - {broadband phone USB modem - Vista Desktop-
Ralink Wireless} - laptop with XP/wireless

Before stating this, had laptop chatting fine over wireless connection. Now
giving it to a friend. They have a desktop with a wired connection to
Internet using Vista.



Have laptop talking to desktop connection working fine.



But it does not get through to the Internet.



What is the magic in Vista to tell it it is to pass a wireless connection
through to the Internet connection it has?



(There is some security software on the desktop (CA something) but I do not
think that is the problem and I do not want to turn it off.)



Bill