Here is a link to a review of one such ethernet over power cable adapter:
http://www.cnet.com.au/wireless/adap...0056722,00.htm
As you can see, they are not without their problems.
You have to be sure that both plugs are on the same circuit. They tend to be a bit more expensive than wireless.
So I take it you can't get a vista driver to work with your wireless card?
Netgear advertise that they support vista:
http://www.netgear.com/Products/Adap...ers/WG311.aspx
One of the problems with Vista at the moment is that not all hardware has compatible drivers. Some XP drivers work, some don't.