Those of you not lucky enough to have the time and money to have outfitted your home with ethernet jacks all over the place probably still have coax cables in the major rooms. A couple tests or a look at some records could tell you the layout of the cabling, then buy this coax conversion kit from D-Link and presto, you’ve got yourself a home networking solution! Assuming wireless didn’t work out for you.
It costs a bundle for a legacy adapter, but if the alternative is tearing down a few walls, $200 starts looking like a real bargain.