Paid Site Ads vs PPC Search Engines

[icp]

Hello.

I've just started an Ad Campaign on Adbrite. It seems, however, that after about 400 clicks I've had exactly zero sales. Not only that, but according to Commission Junction, my affiliate banners have only been clicked 10 times.

I'm thinking of cancelling it and start an Adwords campaign. But first I wanted to ask if there is a noticeable difference in the quality of the leads between PPC Search Engines and paid site ads, such as the ones Adbrite shows. I'm starting to think that because in search engines, users are actually searching for relevant information, then maybe the clicks are of higher quality, than in paid site ads, where users casually browsing a site suddenly see my ad. Any comments on that?

Also, my site is a web hosting review site. Does anyone know if web hosting as a niche, exhibits a lower conversion rate or something? Perhaps due to the fact that people searching for web hosting might be more knowledgeable, or want to conduct more research?

Thank you very much for your time! Any comments or help will be greatly appreciated!

Thanks,
Alex