Wireless security on 10/4/11

When I'm setting up my home wireless network, are there security settings that I must use -or disable- to allow the setup?

I attempted to set up a wireless network about 3 months ago with the "help" of my ISP tech service [ATT] which didn't work at all. After two hours of trying the same solutions over and over... the ATT gal said that there must be somethijng wrong with my Apple. She seemed to reading some script-sheet there on her end. I didn't buy that there was something wrong with my Apple..., however was disgusted with the whole experience and put the project away until this week.

The equipment I'm using is this:

--G4 Quicksilver running dual 1.6 gig processors, 1.5 gig memory, Airport Card, 3ea 250 gig HD with OS 10.4.11 Server software installed, Airport Express BAse Station, new ATT Router, 2ea USB multiple cards, DVD/CD Superdrive.

I don't think I need both the Apple Express Base Station and the new ATT router, however bought the ATT router on the recommendation from the good folks at ATT since my old modem [a Westell] was, well, very old. I'd prefer to use the Airport Express Base Station, since my plan is to get this wireless net up, and then add Apple TV to it.

I'm not sure at this point wether or not the Airport Express Base Station needs to be reconfigured. I'm happy to drop the new ATT router is needed. Otherwise, my G$ is a very happy Mac, with no issues.

Can anyone suggust a plan to proceed with?