The Linksys system I installed in our house is easy and was much less effort than running cables. We do seem to get weak signals at the other end of the house though.
Also, one of the PC's was older and there were no suitable drivers available for the card with the antenna (I still have to run that cable, yuk, and of course it is at the far end of the house).
Yes, you can cable directly from the router to your PC's!
Good luck with it!
