I've looked and haven't found it. Maybe I'm not looking hard enough. Enough people use the icons so I thought a start button would be out there. It is the home icon from the Token icon set.
I can't try it though cause I'm running 64 bit. You know the drill backup your old explorer. So you don't have to reboot to see if it works, just kill explorer in taskmanager and open this one
It has a white outline and there is a little black showing. And whenever I open explorer it says that it isn't signed and asks me if it is okay to run it.