One of the limitations of WiFi is that it's not scalable, and it has a finite capacity. You cannot get more than (currently) 108M bandwidth. You simply won't be able to stream the latest movie in 3D multi-colour to every media computer in your house without seeing some performance limitations. And that is your own performance limitation. If your neighbour has a WiFi LAN, you will also have to share the bandwidth with him (her). WiFi simply does not have unlimited bandwidth, new technology or not.
In any domestic situation with neighbours, for a problem like a loud stereo, the tendency is to turn your own stereo up. Crank that sucker. This is, however, not a good, long term solution.
- You possibly have up to 8 immediate neighbours, and more beyond them. Some of those neighbours, also currently suffering from your neighbour stereo, now have to suffer from yours too.
- Your neighbour will probably turn his volume up yet again, to overcome the new "noise" from your system.
Like every analogy, this one suffers from a major problem. With loud stereos, it's easy to find where the noise is. Just follow your ears. Then call the police, and have them deal with the problem.
If your neighbour has a "loud" WiFi LAN (ie SuperG or MIMO), you won't be able to follow your ears. Nor will, I suspect, the police be interested in becoming involved. You're going to have to find your neighbour, and you're going to have to convince him to turn his stereo (WiFi) down. Or suffer in silence.
You can start with NetStumbler, and triangulate the problem. Then, you'll have to use diplomacy, not technology. You'll not solve the problem by getting a high power AP.
I, and others like me, have seen this situation coming for some time. Here is one possible real life example, and here is a second possible real life example. And even if neither discussion is diagnosed with this cause, this scenario is coming. Channel saturation, and unexplainable intermittent bandwidth variation, will become the norm, not the exception.