Maybe they would help. The spec sheet for the AP doesn't say what antennas are on it now, so I don't know of any way to tell if 9 db is much of an improvement. Probably, and certainly won't hurt, but I don't think I personally would buy them for just 30'. Somethings wrong with that. I think I'd try to find the problem first. If I was getting a signal to my neighbor's house and it was weak over there then maybe, because the problem is simply power. With just 30' and weak signals, you have a problem that may not be overcome by a more sensitive antenna.
Make sure your antennas are pointing straight up if the AP and your living room are on the same floor, and turn the AP so that an imaginary line from the living room to the AP is as perpendicular as possible to an imaginary line between the two antennas, with nothing like a monitor or file cabinet between the living room and AP. Also, try changing the channels around...you might have some interference. But then you may just have walls opaque to RF...a lot of older houses with plaster walls used wire mesh - "chicken wire" - in the walls as a binder and it creates a kind of Faraday cage, blocking the signals.
If you are looking to improve the signal from one room to another and not much anywhere else in the house you might look into directionalizing the antennas. As goofy as it sounds, rigging up a reflector of card stock coated with aluminum foil actually does work somewhat. Check out some simple designs for a parabolic reflector - HERE (http://www.freeantennas.com/projects/template2/index.html>HERE</a>). A bunch of home brew reflector pics - <a target="_blank" href=http://www.freeantennas.com/projects/template/gallery/>HERE</a>
Seems kind of silly, but I believe I'd try that before spending some money on antennas that may or may not work.
Josh
Yet another site soon to be neglected:<font color=green>
<a target="_blank" href=http://www.zachmax.com>www.zachmax.com</a></font color=green>