Today the latest version of [openMSX was released for Win32 platforms as well. Although Reikan, the developer of this port, is also involved with developments around the Linux version of openMSX, this version is still to be considered as an unofficial port.
The previous version of openMSX 4 win32 already did an outstanding job at emulating the MSX. However, quite some things could still be improved. The changelog is the same as the changelog of the Linux version we reported about earlier.
Relevant link: openMSX unofficial Win32 port website