You only need to distribute one file:
xerces-c_3_1.dll for Windows
libxerces-c-3.1.a for AIX
libxerces-c-3.1so. for Solaris/Linux
libxerces-c-3.1.sl for HP-UX on PA-RISC
libxerces-c-3.1.so for HP-UX on IA64
libxerces-c-3.1.dylib for Mac OS X
Note, however, that if you built Xerces-C++ with dependencies
on other libraries (e.g., ICU for transcoder support or libcurl
for net accessor support) then you will need to ship those
libraries as well.
You can also link your application to a static version
of the Xerces-C++ library in which case you won't need
to distribute any extra libraries.