I've always been dubious about this technology, something just doesn't sit right about the ability to send 240V of mains power and data along the same cables.
Anyway, I had a wireless game adaptor behind the TV, linked to my xbox and xbox 360 for connecting to live and for streaming video from my PC. My wireless router is a cheap crappy one, and pretty much every time I want to connect I need to reboot the router then reboot the adaptor to get them to connect up (this is the fault of the router - Sweex - rather than the Netgear adaptor, never had a problem anywhere else with two netgear products connecting wirelessly). Anyway, it was getting to be a pain in the arse.
So, after a recommendation, I decided to purchase a pair of
Homeplugs, thinking there's always eBay if they turn out to be crap.
About 60 seconds to install the things (one in the power socket by the router, one in the power socket by the consoles), and I now have a permanent wired connection to the router - through my mains power circuit. Xbox live is fine, and streaming video from the PC through Xbox Media Centre is also no problem.
Hooray for Homeplugs, I guess.