You probably just need to make sure your PATH variable includes X (usually at /usr/X11R6/bin). So:
Then try running configure again. There is a way to automatically add X to your path each session, but it varies from distro to distro.
Note: please include more information when asking for help. Fill out your distro in your profile, and include versions of important software, like your distro, kernel, and desktop environment. For instance, in this case, the version of Kopete you are installing and the installed version of XFree86 would have been useful.