Read this article
to do it like a pro...
...or use this tool MyUSBonly
Now I did download a 'free for non-commercial use' version some three months ago, but it is not free anymore.
I can mail you the version (2 Mbyte) I download if you PM me with your mail-address.
Don't know if this version still works or not, but at least you can give it a shot before you buy
I did test it at the time and it works. Had to de-install it though, because a lot of people came by with digital camera's so I needed the ports again.
After doing a Google I also find a registry tweak
that should do the trick. You will need this tweak
to enable writing again.