imac with no wifi

Hello,

My friend has an older imac with no wifi inside and shes just got herself a wifi connection at home.
What does she need to buy to insure a connection to the wifi router, Im a bit lost with the airport system.

thanks

A USB wifi card should do.

voiceofra said:

A USB wifi card should do.

Click to expand...

I bought one a while back that is one of the few compatible usb wifi cards but it freezes the computer all the time.

How does the airport system work and which would she need, Im not sure of the difference between the extreme and express.

cheers