Im not sure what would be better, a landing page for your adword visitors, or having them go directly to the affiliate site itself.

The af. site is designed to sell and have excellent conv. rate, but with your landing page you recieve targeted email subscribers, whom you can send info, and ect to.

So which is better????

if your sending them direct to an affiliate site, then you are just doing the marketing risk (and potential profit/loss) for your affiliate provider, so I would say a landing page where you can gather more info about them, create brand awareness etc, and who says you can't sell the product better than your affiliate site anyway

Pre-Selling is an art in itself. If you have a landing page, I wouldn't try to directly sell them the affiliate product, just give information about the product, like a review.

I'd also set up an e-mail campaign with an auto-responder, that way you can get e-mail addresses to promote to.