There is also the Google IME which is pretty much the same but in long run it’s probably better.
Google IME Download – https://tools.google.com/dlpage/japaneseinput/eula.html?platform=win&hl=en
To enable either just go to Control Panel > Clock, Language, Region, > Region Language > Keyboards and other input languages > Change Keyboards > Add > Japanese > Select either Google Japanese Input or Microsoft IME
And to use Microsoft press the little EN on your taskbar, switch it to JP.
And to use Google right click inside a text field and click Open IME.
Here is a video tutorial just in case. http://www.youtube.com/watch?v=g5zpoYHlNT4