Well, PLs could be a good solution, only thing is that if your power lines in your house are not good or something happens to them, makes it kind of hard to trouble shoot.
You could set up extenders if you still want to keep the router where it's at, however I would recommend getting it more centrally located on the main floor of the house. Then go from there and give a extender a try or put in a DAP bridge for the one PC in the basement, you wouldn't have to install a WiFi card in the PC, just connect the PC to the back of the bridge using the LAN cable.
I might phone contact D-Link sales and ask what they might recommend after you give them some info about your environment.