Problem connecting through internet with wireless

I have just purchased Dell Latituede D620 few weeks ago. It includes Dell Wireless(TM) 1390(802.11g) MiniPCI Card. And I am now using Window Vista Business.

 

Problem is that I cannot complete  some the wireless connection processes. For example, when I connected through internet with wireless at home, I can connect. However, when I connected it at my office, I cannot(WEP Key is correct, all lights which indicate that wireless is opened, and all settings are properly set). When I clicked connect, the window box said "Windows cannot connect to...................." Ha Ha. Well, there are another thing that surprise me. When I put wireless card into PCMCIA port, I can travel through internet but the notebook will stop working few minutes when I open Utorrent program. Thus I have to Shutdown the notebook, then boot it again. Also if I am not open utorrent, I can travel through internet without any problem

 

Please tell me how to get through this problem or tell me which wireless card would properly work with my notebook.