Thanks for the quick reply,
User registration won't be a problem mainly because they all have a membership ID. The user doesn't register, I have an entry for each member who can vote.
Well, hackers are stopped 99.(9)% at the stock exchange, visa, paypal, etc. All a hacker can do is ddos the hell out of those servers. I never heard of a billion dollars stolen in fraudulent automated bot trading, or visa being hacked or paypal or the 3D secure servers (and there is a different 3D secure provider in each country)..so it's possible to 99.(9)% hackproof it.
I'd like to know ways of how an attaker would go about to steal votes.