Extending a Wireless Network?

[thomas__hb]

Hi all...
Im about to move house in the next week into a two storey terrace house. I currently have a DLINK DSL-604T Wireless ADSL Router that connects to my only computer via a CAT5 cable. I bought it originally because it was on special and therefore cheaper than an ADSL Modem/Router without wireless, and it meant that my uncle who stayed with us while in town for business could connect easily.
My brother is muttering about getting his own computer at our new house. The desktop/router is going to be on the ground floor at the front of the house, and his new room is the one at the very back of the house on the 2nd Storey, which is a stright-line distance of about 20 metres. He also has a Playstation2 that he would like to connect.
I suppose my question is, should I install an external antenna with a 7dB Gain at each end and hope that that's enough, or something else?
Im not sure what exactly...i think it might be a repeater or a bridge?
The reason why I think i'll need SOMETHING is that at my current home there are plenty of dead spots on only the ground floor.

The house is built in full brick, and the walls are plastered so i don't think the signal will permeate the wall to easily.

Any Ideas?

[blue60007]

How old is the router? my wireless router has excellent range. I can go 20 meters and downstairs and still have connectivity, even going outside another good ways. My house is also brick and some walls are plastered (but I'm not sure if plastered walls will reduce the signal any more than plaster board). I would try the router at the new house before buying anything.

[thomas__hb]

The router is less than a year old...and is 802.11b/g compliant if that makes a difference to range rather than just speed...

[thomas__hb]

I suppose on a separate and more theoretical note, i have another question...

If hypothetically there is a poor signal between a computer and a Wireless Access Point, if a high gain antenna is added to the Access Point, does there need to be a similar antenna on the computer, or does the one higher gain antenna on the access point compensate for the shortcomings of the other?

A good analogy that i remember reading somewhere is that wireless networking between walls or over long distances is like trying to have a conversation with someone next door or across the road. And adding a newer, more powerful antenna is like making your ears more sensitive and your voice louder, but with that, comes the fact that you can now hear a dog barking more loudly and the car driving past is nearly deafening.

Is this the case? And does having ONE high gain antenna compensate for a smaller one on the other end of the "conversation" like compensating for someone with a hearing problem.

Any Ideas?

[glc]

You probably will need high gain at both ends. The gain really only affects transmission, not reception, and it must be a clean 2-way communication.