<p>Does anyone know of a good Java API for controlling RS-232 devices in a WIN32 enviroment?
I've tried RXTX but they don't support RS232, only RS-485.</p>

What about
J/CoMM
?
OS independent RS232 remote control. Java-based server (console), easy adjustable HTML GUI, local/internet use, incl. device driver API and drivers (e.g. EIKI LC-XM1/SM1/VM1!!)