Hello,
I'm not a Windows user, so can't help you with VS. But I can point at some moments that you need to know to build libstrophe in general.
First of all you need to be aware of parser and tls "modules". You must add exactly one tls and one parser implementation to the project and omit the rest tls_* and parser_* files. I would recommend to use parser_expat.c and tls_openssl.c. Other files you must not add to the project are oostanza.cpp and oocontext.cpp.
Second, make sure compiler finds strophe.h. Just add path where it's located to the heades path.
Third, you need to manage external dependencies what includes expat/opennssl header files and libraries. Sorry, I can't help with this part.
There is a way to build libstrophe as standalone static library without dependencies, but without TLS support. Simply add expat sources to the libstrophe project and use tls_dummy.c instead of tls_openssl.c.
Also, check this pull request:
https://github.com/strophe/libstrophe/pull/15 . It adds project files for VS2012. Other thing that may help you is cmake project files.I believe cmake has Windows support and you can find libstrophe forks on github with added cmake files.
Dmitry.