goto your HD and browse to the Microwin.exe file.
Enable the file, press the right mouse button and open the properties´.
Here you can find a tap named "Compatibility"´. Now select WindowsXP mode and try. This may work.
I do not know if there are limitation (Multimaster mode, Ethernet, USB-2-RS232 converter, .....).
Basically the actuall MicroWIN version is not supporting Microsoft Vista.