I don't know about the Intels, but the fax software that comes with OS X.4 works fine for me on my G4 QS 2002.
She will need the external modem to send/receive faxen with the Intel Macs.
To send a fax (contents of the document you're working on, or anything you have open, do a command-P. Then click on the PDF button on the lower left corner of the resulting print window and select "Fax PDF".
To setup for receiving faxen, go to the Syatem Preferences and click on the Print & Fax icon and proceed from there.
You can define a folder where incoming faxen will reside.
The only thing I don't like about the built-in capability is the inability of the incoming fax to be recognized as a fax vs. a call. The resulting shriek in the callers ear is not desirable. So I set my computer to be in idle mode, then manually activate when I expect a fax.
Hope this works with the Intels.
Anybody out there that uses the Intel Mac have any first hand user experiences? Put in your 2¢ worth, or correct me if I'm totally off-base. It won't be the 1st time!
Jack