wireless configuration

OK this may be easy but i’m confused. I bought a linksys wireless G. I have a laptop with build in wireless and a PC hardwired. I can get both PC and laptop to get online, but it’s not secured. When i go to secure the connection, i get an IP address conflict and from there neither machine can get online. Why? it shouldn’t work when it’s unsecured either, and that’s why i’m confused. Any suggestions. Please i’m frustrated with this thing..