How would I ethernet to the other side of the house

Hey guys,

My house is fairly large and I'm having to use wireless to connect my desktop in my bedroom to my router which is downstairs in my office. Unfortunately the wireless signal isn't so great and tends to cut out quite often - which is annoying. How can I get a wired connection from my router downstairs to my desktop upstairs in my bedroom. I've looked into homeplugs but do these slow the connection in any way? And I'm not sure if the plugs are on the same circuit - does this matter?

My current router has an option to put it into 'modem mode' which basically just turns it into a modem. So would it be possible to use my office's router as a modem and use the homeplugs to connect to another router in my bedroom to actually transmit the wireless as this would be more central in my house. Also would I just be able to plug my office computer into the 'modem' router in the office when it is in modem mode and still have it on the same network?

Thanks in advance for your help.

Also I suggest creating a section on the forums specifically for networking?

http://www.amazon.com/RiteAV-Cat5e-Network-Ethernet-Cable/dp/B00139VKV0

Thanks for the obvious but I don't want a massive wire trailing through my house - and I can't go under the house or in the roof without making a hole in the wall, which again, I don't really want to do.

Do what I did, buy another router, hook it up to the router from the office. Just staple the cable on the wall. That's what I did LOL

couldnt you use a powerline setup, or perhaps just a wifi enhancer thing, like a second router which hooks onto the third one.