Trust me on this, wireless is really really really not worth the effort.
everything in your house will interfere with it from walls to lights, cookers to fridges.
I have set up and configured a couple of enterprise grade wireless systems and i have always found them to be hard work, they normally work well in open plan places, or places with thin walls. Thick walls and metal work will kill connections.
also dont belive this etream G stuff that D-link pedel, you will NEVER hit the top speed,
eg.
54mps wil never hit 54mps. you would be lucjy to hit 30.
if you do want to use a wireless system, i would recomend Proxim, Cisco (if you have the money) or a belkin box. Dont be tempted to buy a cheap one as they normally dont produce results.
also if you are having issues with range, it may be worth bridging between locations
this envolves using 2 or more AP (access points) to extend the range.
iuf you want any more info just ask
Steve