I dunno man stuff popping up in my window is exactly what I call intrusive. With adsense at least you see the ads right there and then and don't have to go: "Oh I want to learn more about linux (which is double underlined) click BAM: BUY SOME RED HAT BITCH"... thats just me though. I have never been too big of a fan of ads on sites, but then again I have yet to have to pay for hosting or any of the other wonderful things that most peoplehave to do :).