As far as I'm aware, your site is still perfectly legal. (As long as said script kiddies have not ripped off the design!)
It is not your (the design client) responsibility to ensure the designers have legal copies of software - it is only they who are breaking the law. This being said, you could be in trouble if you continue to hire said designers after discovering their software is illegal (it is like hiring a joiner who doesn't pay tax - as the prices are cheaper, you are profiting from the proceeds of crime) and may face charges on this count.
(This is the law as I understand it, anyway.)