i really cant understand the question...
Ive networked countless houses with HPNA cards.
Ive done it successfully with Linksys cards, Diamond HomeFree cards, and the discontinued line of 3com cards.
I RECOMMEND HPNA TO EVERYONE.
HPNA requires that all computers be on the same PHONELINE. So if you have 2 phonlines in the house all computers you wish to network have to be on one or the other. Hell you can have multiple networks in the house if you have more than one phoneline.
Ive also networked someones house whose house has REALLY old phone wiring. Like there are 2 lines thru one connection. There are two splitter types, one that splits a connection into two, allowing for the connection of a fax, HPNA, a phone, etc all on the same line. Then there is a splitter which will split a single connection carrying 2 or more lines into the amount there are. That is what this guy had, which required the purchase of these specific line splitting connectors. In the end i got it working.
As i already said, as long as the computer can be on the SAME phoneline itll work.
As far as there being 2 holes on the back of the cards, it allows you to daisy chain computers, up to 30 of them, or connect a phone (or fax) that was previously connected to the wall. The phone will still work flawlessly (and even a FAX machine will still work flawlessly). From what i know, it doesnt allow you to connect to multiple phone lines.
I highly recommend HPNA. And the diamond homefree cards are detected flawlessly in windows XP.