Speaking from a consumer (computer user in this case) standpoint I would never download something that comes up as a pop-up. Direct linking for your kind offer is not going to lead to any positive results anytime soon. Just look at how people are being trained on viruses/malware etc. the status quo is don't download things from pop-ups.
As for some advice create landing pages if you really believe in the campaign you're trying to capitalize on. Create landing pages that include videos of you using the software to show people that yes it does work and yes it's a worth while download.
Like I said in the first paragraph your campaign is a tough sell, especially so if you're using PPV to market it. I'd say try quality (informative) landing pages, but if you're still not seeing anything positive drop the campaign for PPV. PPV is only good for a few niches in my experiences, and I've never got much traction with any offers that require downloads from the users end.
A good avenue for download driven offers is PPC (Google or other avenues) or just buying banner ads or text link ads on websites or blogs that are relevant to your offer.