Well I'd be real surprised if you could get 25% of people to agree to download something and install it.. but would love to be wrong
If you can't sell it in bulk first step i'd do is work out where the surfers are coming from. And send to geographically appropriate sponsors..
Re: casino programs i've had some good sucess with mainstream 404 traffic but often it needs more patience than you're willing for, like you get one big loser that makes it worth your while..
At the moment i'm trying 404 taiwanese traffic to a casino.. no results yet..