Squawking 7500 here !!!!
I'll take the US approach and come shoot you down.
But, if you want to persist at the wireless route, try something "N" based... eg. one of these.... NETGEAR WIRELESS-N SERIES CABLE MODEM ROUTERS
I gave you a big hint in the right direction many posts ago. From there I'm afraid you'll have to do your own homework and buy from somewhere reputable that will not make a fuss over returns.
WiFI is a black art in the el-cheapo domestic market. What works for someone might not work for someone else and vice versa. Cheap domestic rubbish is very dependent on how the blackbox itself is constructed as well as the construction of your premises. The advertised range figures are nothing but a load of codswollop.
To give yourself the most flexibility, I would suggest you look for something with an external antenna option, not just internal ones. One that supports plugging in a decent range of alternative antennas to boot (i.e. not some dodgy proprietary connector) That should give you extra options to play with.
Should also check what's built into your PCs/Laptops is compatible, otherwise budget for extra cards and dongles.
Sorry, but that's the truth.