Is there any plug-in available in Geneos to monitor WINDOWS disk I/O speed capacity. The Device IO plug-in is currently supported on Linux and Solaris platforms only.

There is. You can either use PerfMon or WMI plugin. In this example I choose PerfMon since it is more straight forward. The reason behind is that, I do not need to know the win32 class object to get the data. By just running the netprobe exe file with -perf flag, it will show all objects that can be use. Below is the xml example and the screenshot result.