I'm that strange breed that gets the full version off the net and then feels bad if the game is good and buys the full version anyway. I mean, I'm a programmer too and wouldn't want my work pirated. I did this with AOE2, a couple command and conquer games and SimCity 3000. IF the darn stores had some of my other games I'd get those too
I've rarely installed demo versions It feels weird to me. I'll open the start menu, and there are a bunch of games with the capital letters "DEMO" at the end, Screaming, "BUY ME! BUY ME"- although I'll admit some less desireable titles scream "UNINSTALL ME!" instead.
I hope my first paragraph doesn't break any forum rules... (?)