Recently, I installed Ubuntu 8.10 on my notebook which contains RTL8187B WLAN card. unlike previous versions of Ubuntu which don’t detect such card, 8.10 detected the card, and WLAN worked very well. But I noticed that the range of the WLAN is very short, and after very few meters from the router, there is no traffic. After some long search, here is the solution that worked with me:
1- gksu gedit /etc/rc.local
2- Add the following line to rc.local before exit 0
iwconfig wlan0 rate 5.5M fixed
3- Reboot
Of course there are some other solutions based on ndiswrapper or the modified RTL8187B driver, but I found the above solution powerful and easy and no big change happened in the system.
Techii 
It worked, and after a week of sitting in a chair in front of the wifi, i now can finally lay on my bed…
thx man.