Two Story Network Setup Help

This is my first 2 story networking setup I've come across in my various living situations and need some help. Let me describe my current setup:

I have a 2 floor townhouse with the living room on the first floor. In my living room I have my entertainment center with my TV, PS3, 360, Cable Modem, and Cisco Linksys Wireless Router. I have the PS3 and 360 connected to the router via ethernet cables since they are only about 4 feet from the router and i use both for Netflix/video streaming as well as online gaming (of course). Up until now I have just had a laptop and tablet, the wi-fi downstairs is amazing but upstairs in the bedroom or guest room it's about 2 bars strong which is totally useable for the Laptop and Tab.

Ok, here comes the problem. I am finally building a mid-range gaming rig, something I have always wanted to do and finally have a budget to afford. BUT, the PC will have to be upstairs. I will always prefer and fight for a wired connection for a desktop PC, especially for gaming. As you have seen from my current setup, all of the wires are downstairs. To add to that, I cant run any cables to the upstairs or drill or add anything to the house (renting, not owning).

So the main questions:
Any recommended setups for my situation?
Do I move the Modem and Router upstairs to have the PC wired and put the gaming consoles on wireless?
Do I try powerline (the townhouse was built in the 70s, not certain of the circuit situation)?
Do i get a range extender and just connect the desktop on wifi?

I thank everyone in advance for their assistance!