WIFI connection for a 2wire modem on windows xp

First, provide more infomation.

What type of system do you have? Laptop or desktop? Does it already have WiFi hardware?

Is the modem built into the machine, plugged into a card slot, or a separate device that is currently attached to your machine with a cable, or through your network?

My problem is that I don't know if you are trying to attach two separate devices with WiFi, or make a machine share its modem connection with other machines via WiFi. I know that you will need WiFi hardware for at least your PC. But I need more details to give a meaningful answer.

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Answer without clarification, since people seem to demand these: Buy a wireless access point and connect it to the modem's network port. Buy a WiFi ExpressCard and plug it into your notebook's ExpressCard port. Set them up to talk to each other.