Wireless Problem

Alright.

I'm completely illerate in terms of knowing anything in terms of PC and networking so bear with me. I'm connected using a Dell TrueMobile 2300 router with a Westell modem. I currently have my Dad's PC connected to the Internet through an Ethernet. So I'm assuming that having a PC with a wired and wirelss connection is called a Ethernet bridge correct? I have a wireless USB Robitics Adapter card to connect to the Dell TrueMobile 2300. The problem though is that I've been getting low to weak signals on my wireless card and I can't seem to get online for more than a few hours. I'm assuming that the Encryption on my wireless U.S. Robotics is not the same as on my Dell TrueMobile 2300? From what I've read, the Encryption allows connection to be passed through each computer while connected to the Router? Please correct me if I'm wrong. I need an FAQ or guide to show me how to fix my Encryption problem so that it'll match on my Router and wireless adapter card.