just installed a new time capsule and i want to use my airport express to extend my wireless range....time capsule working with existing devices at this time...but i am not able to get airport utility to recognize the airport express.....????

Always plug things in via ethernet and use that to do the setup.. you can then disconnect it and use it in the network.

Temporarily connecting your AirPort Express to one of the Time Capsule's Etherent LAN <-> ports...as LaPastenagure suggests....is always a good way to setup and configure other network devices.

If you want to configure the Express using wireless, remember that the Express broadcasts a default wireless signal with a name like Apple Network xxxxxx. You must log on to this network first....no password is required....then open AirPort Utility to "see" the AirPort Express.