How to solve this problem? Wired internet connection?

powerline networking is the way to go. You plug a powerline adapter into one of the router's free ethernet ports and a nearby mains socket, you can then plug another powerline adapter into an upstairs mains socket. You can now get powerline adapters with 3 ethernet ports which would seem ideal for your upstairs situation
here are your links, before you buy I would check with solwise that they will work together
http://www.solwise.co.uk/net-powerline-av-3pe.htm
http://www.solwise.co.uk/net-powerline-av-push-piggy-mk3.htm

HTH
David

You can use powerline (formerly known as home plug). It is basically 2 adapters that plug into your homes power sockets, and you plug an ethernet cable into each.

Example: You would connect an ethernet cable from your router to your power socket, and then where the Xbox etc is upstairs connect an ethernet cable to the power socket near to that.

you can buy an access point or a range extender.
You can also buy a powerline adapter.

Gonna be honest, not 100% sure what you're asking, but I'll give it a shot. I'm assuming you want wireless for some of your devices, while still having a wired connection? In order to have wireless internet, you're going to first need a wireless router, which by saying your laptop is already hooked up, that seems set. You can trail the wire, which is honestly not too bad, (this is where my thinking is getting a bit hazy to due the question) you can get a PCI card and install it into your PC for wireless connection. There is also a USB dongle you can get that could work on obviously any device with a USB drive. It's relatively easy, and you shouldn't have a problem with doing either. Just look up "Wireless PCI card" or "USB Dongle" and you'll have (what I'm assuming) you will need. GL

You can buy an Ethernet splitter, that will let you use one wire for two connections. Also, you can try wiring better? Start drilling some holes boy.

And yeah an EOP will work with your Xbox, but again you're probably going to want to get a splitter if you're going to be using more than one connection.