Wireless security GWART2-54125

I'm using the above router and wanted to improve my security. I have my desktop wired to it and have one wireless laptop. The laptop is connected via a USB SafeCom adapter. I tried setting up WPA but ended up shutting out the laptop. I enter the same 63 digit code on to the usb adapter software but made no other changes. In the end I gave up and switched off the WPA on the router. I have enabled the MAC list and entered the correct numbers for my laptop on to the desktop. I'm now reconnected but concerned about security.

The instructions that came with the router and usb adapter are not very helpful regarding setting up security. Should I do more and is there a sticky that will guide me through the process.

Thanks

Si