you say you have been to GRC... you seem to have missed looking at the 'network bondage' page at that site. Suggest you have a look at it , it's here

http://grc.com/su-bondage.htm

It is much more permanent that simply turning off file/printer sharing and gives some insight into protocol bindings. But I would suggest you read it thouroughly before you attempt it.

hope it helps

Z