I wanted to network the xbox in the livingroom with the router in the office. Wireless tends to be sub-optimal since German house construction is mainly concrete-based, which impedes the wireless signal.
Running Cat5 through the house is impractical again based on the walls being solid concrete in the areas I want to network.
So I thought I would give Powerline networking a try. This is using the electrical cabling in the house to carry the signal. Since our house is only 2 years old, and Germans tend to use rather robust building materials, I thought this would work out well.
I went with Netgear and bought the HD Powerline Ethernet kit, which claimed 200MPS speeds on the box.

Then I noticed the connection were being lost and regained over and over again between modules... and the speeds were slooooooowwww. I installed and ran diagnostic software and found the living room module was only getting 4 MBPS. I unplugged and replugged and saw performance increase to 28MBPS, which is still far far from 200. The connection dropping/reconnecting was also too terrible to deal with, so it all went back to the store.
I dont know if the issue was my wiring, or the modules, but I decided to go the wireless route instead.
I purchased the much overpriced MS Wireless Xbox Adaptor.

I am not sure if changing my router to a better one would improve things, or possibly adding a repeater someplace in the middle. Eventually I will get it all sorted, but I was really hoping for a wired solution with some high speed, so I could better stream video and audio.