Problem with Router and connection

My router is in the conservatory on the ground floor with my modem next to it, my computer is next to them both and wired so obviously runs fine.

However, when I take my Xbox 360 up to my room which is at the front of the house the signal doesn't reach and so I disconnect, is there anyway I can make the connection stronger and reach further?

i think only wifi would do that how ever microsoft as write deinformation adds :
GET Out of the WIRE ! play WIRELESS With microsoft wireless ! don't worry if ur ping drop from green to yellow !
eveone will be happy we are microsoft after all and don't care if costumer cry cause the game lag :) and i got xbox live
and you can tell how i get angry at lagger ! :) after it i leave game
cause lagger i shoot them bullet in the head they don't die like if the game was not lagging :(
http://www.youtube.com/watch?v=UFTtho7jkto
http://www.youtube.com/watch?v=J2rOkhvSSqQ you see hole aren't formed befofre 15 second
that wut happen if you log with people in mexico. with 1.0 megabite per second internet speed
a bit off topic but just a point of view that lag isn't a illusion it a reality and wifi contribute to it :)

so you can do test wired or wireless. i fit wired im glad to know your ping is not red like in those video :)
else well i can tell you people will complain if they ever found out that ur the lag cause lol

You can do some funny things with wireless signals... such as using your house's electrical lines to extend the signal.

But you will find it's better to play wired over wireless.