Weak Transmission

I just bought a wireless dell 1150 inspiration laptop with a dell 2350 broadband router ,  the computer i linked it to is upstairs  ,    sitting next to the computer with the laptop  i get a very strong signal but downstairs and no more then 60 foot from the router the signal is very low  ,  other then the signal being low its working fine,,,,  can someone tell me why its low or how to boost the signal  

 

                                                             thanks