Fishes?
Really?
4 publicly visible posts • joined 1 Jun 2010
Solidcore have a good solution for this type of 'defenceless' system - At least it used to before it was bought by McAfee. You can still get to the Solidcore website at Solidcore.com for info or look at the McAfee 'Application Control' product.
Should tick a few boxes - Low system overhead, AV, no signature downloads.
Might be worth a look.
I hasten to add that I have no connection (and never have had) to McAfee or Solidcore - I just think Solidcore came up with a good solution.