Just chiming in here, but if I remember right, most of the impaling options to kill a vampire (stake through the heart, iron nail through the head, etc.) were just some sort of symbolic way of "pinning" the thing to the soil of its grave. But most of the "vampires" that were killed in New England back in the day were just dismembered and burned though, I think. (keep it straightfroward, I guess)
Plus, if you buy into the newer "theories" that vampires are quasi-spirit creatures, anything with iron any it would hurt them because cold iron disrupts spirit energy.
...I dated a witch, okay?
There's a book out now called "Monsters" written by some "druid" guy named...er...let me check...John Michael Greer. It has some fairly interesting stuff in it you're into monster "theory", including a huge chapter on vampires. Interested parties might want to give it a look.