Horror Campaigns

[bugsysservant]

I'm thinking of running a horror campaign and want to know: how feasible is this with d&d? I have looked through Heroes of Horror, but that seems more up to providing brief adventures, or spicing up undead encounters. The only long running mechanical change it made would be taint, which, frankly, is a bit ridiculous, and I wouldn't use it anyway. ("You failed a fort. save after wandering into some dark woods. You're now gross looking")
My instinct would be to look into CoC, but I have never played, nor do I know much about it, and would prefer to not have to buy another game. Are there any major tweaks that can be made to D&D that would make it less "high fantasy"-ish? Are they even needed?

Edit: Yeah, my intention was more along the lines of "the darkness of human souls" than "you hit the vampire. It dies" Also, one of he best rule variants (IMO) in Heroes of Horror was that for ressurection to work you need someone of the same alignment to sacrifice themselves, to bring back the dead character, and I thought that was most appropriate. I think removing clerics would be a bit exteme though.