I know pulling cat5 or cat6 cable through the house is not fun cos I did it recently as documented here: http://www.extreame.net.au/topic/4050-my-home-network-build/
I did get cable to every room and managed to use existing wiring to pull the wires through to existing face plates except for one room that I resorted to external wiring utilising the same conduit that I used for an external wireless access point. I was able to use phone wires and TV coax to do this rather than have to drill holes through the wall braces. Network cables are meant to be kept separate from power lines but in an earlier house I used the power cables to pull the network cable through without ill effect. I used cat 6e cables, switches and connectors which is a bit more expensive but is the current standard.
I've been sharing cable via wireless for 8 years or so and still use wireless for a number of devices. A good wifi hotspot should give you wireless coverage over the whole house and in my experience newer hardware has a better signal and coverage than older hardware. my cable modem is at one end and my Netgear WNDR4500 modem. The fact that you have a 54 mb Wireless G card indicates that you have older hardware as the newer hardware is Wireless N which is 150-300 mb. In the past, I used external antennas on the router and network cards at the far end but with my current wifi hardware, this is not necessary. I looked at the power wire systems and thought for the bandwidth they were fairly expensive but are great in units where the walls are solid.
I am very pleased with the end result and the ability to hardwire in most devices to a gigabit network. Not every one wold botherbut I think th house is now future proof (even if I need to pull some more wires for my weather station soon...