You can also change the icon to whatever you want.
And here is a tip that will save anyone who still doesn't know about it a hell of a lot of time:
To change the icon of an item in the dock, you DO NOT need to follow the time consuming sequence of right click it, select Item Properties, Change Icon, etc, etc...
Just open the folder with your favorite icons in Explorer and drag the new PNG/ICO file directly over the item you want to change the icon to (it will start glowing) and DROP.
Provided the file you are dragging is an ICO, PNG or TIF image file, it will automatically replace the icon of the item in the dock you drop it into. This method is also perfect to quickly replace multiple icons in the dock (drag, drop, drag, drop, ..., done!).