Speed and connection

Is there settings that I can apply to get my speed up/consistent on my laptop when I move away from my wireless router? I have the router in the garage and my office ajoins it, so when I am in my office I get 54 Mbps and Excellent signal strength but when I move 50 feet from the router my strength falls to low and my speed is 36. Thanks in advance.

 

Inspiron 9100, 512, 2.8, 60, 1350 WLAN internal pci card, Linksys WRT54GS/Speed booster router.

 

P.S. I know there is a "signal booster" from Linksys for about $90 but I did not want to put anymore elements into the network at this point. I also saw some "oversized antennas" for about $50 and that is almost as much as I paid for the router!!