As well, is the router to laptop path perpendicular to the walls or at an angle? I've found this to make a big difference. There are some published approximate loses (measured in dbi) for certain materials such as wood, concrete, drywall, etc. that you might want to look up. It wouldn't be unusual to lose 1/2 your signal through a single cinder block wall, for example. You can also experiment with using different channels. Another nearby router or AP on the same (or near) channel can interfere with your signal. You can try channel changes, router relocation (make a more perpendicular path) or antenna adjustment for best signal.
I have a linksys N router two rooms away and a Dell vostro laptop. WHen I'm in the room with the router my speed is great, but when i'm basically 10 yards it drops way down to 13 Mbps. there is a steal beam in a ceiling that rounds between me and the router when i'm in the other room so i don't know if that's what is causing the problem, but i'm hoping there is some adjustment i can make or booster i can to avoid having to try and hard wire my office. not sure where to start, any help is appreciated!