The windows agent check_mk_agent.exe should run on all Windows-NT based systems. It has been tested on Windows-XP professional and several Windows Server variants. Please tell us, if you experiance problems on a certain version of Windows. Also you might want to tell us, if the agent is running fine on a particular Windows version so that we can publish a list of supported systems. You can compiled the Windows agent yourself using MinGW - the minimalist GNU compiler for Windows. It's homepage is http://www.mingw.org/.