Media for High gain antennas at both ends?

High gain antennas at both ends?

First, thanks for all the informative posts in this newgroup!

Here's my situation:

I plan to set up a PC on the thrid floor of my house. The cable modem/router is located in the basement, perhaps about four feet underground The distance between it and the upstairs room is about thirty feet horizontal,, thirty feet vertical away. This is a brick house build c. 1940..

The router is a Linksys WRT54GL router v1.1 flashed to DD-WRT .

Using a notebook with a Hawkings HWC54G card (not a Hi-Gain model), I am getting about -45dBm from a position one floor up, and about -72dBm two flights up. The Linksys router antennas were positioned perpendicular to the desired locations. Increasing the transmit power from 28 to 48ma improved the signal just two-three dBm, as indicated by posts in this forum.

While the signal on the third floor is rated poor/bad by the Hawkings ultility, and generally gets just two bars from Windows; the signal is steady, I didn't have any particular delays in getting webpages or downloads, and I got Speedtest scores of about 6mbits/sec, or about

65% of wired speed.

Given that the signal needs to get to a fixed point, it would seem that a directional antenna would be the best answer. Having seen the discussions about transmit power and the need to have both ends transmitting at about the same power for it to do much good, what's the case with antennas? If, for instance, I had a 10dBm directional antenna attached to the router, and a 10 dBm antenna upstairs, would I end up with double the improvement (assuming all was aligned correctly), or would I have just whatever improvement in each direction that came from each antenna?

I guess my real question is: Do these hi-gain antennas improve both transmission and reception, or just transmission?

Assuming that DIY is not an option, what would be good but fairly inexpensive (i.e. not much more than $50) manufactured directional antennas that would be compatible with the Linksys router? Does the use of adapters (i.e.SMA to TNC) hurt performance? If appropriate, I'd also like to know about good antennas for a PCI card and notebook cards that can handle a good antenna, too.

While I may do file transfers down the road, in all likelihood, this connection will be almost entirely for a plain vanilla Internet connection, no video streaming or P2Ping or torrents, big file downloads will probably be as strenuous as it will get. While I'd like to get the signal better, maybe I'm gilding the lily?

Finally, is there anything important I've left out?

Any answers or links would be deeply appreciated. Thanks!