Ok, tell you my senerio, currently my intention is to set my TC as my base station. My window PC will be wired to TC. My MB will be wireless to TC. My internet currently will be wired to my TC through my Linksys modem/router. Maybe in future, my internet will be wireless link to TC, by adding a Airport Express.
First, how you set the TC to be a base station? The questions in the setup very confusing.
Next, is it everytime need to use airport utility to change any of my setup? My problem starts when I start changing settings on MB and PC. I think it is what you suggest change to DHCP to solve the issue.
yup..use airport utility. it will detect the tc automatically. for a start set both mb and pc to dhcp...then later if you need one or both to be static then change later. or even better use the dynamic IP reservation to almost guarantee each will get a specific ip.
btw..did you check out the setup guide? see page 15 to use tc to extend your existing network. got diagram.
http://manuals.info.apple.com/en/TimeCapsule_SetupGuide.pdf
edit: should be page 15