The Dungeon Magazine module "The Dying of the Light", penned by Chris Doyle had extensive rules regarding combat with vampires, and how you could kill them. I think it was only a variant rule, but I have used it, and I like it.
First off, the module was about the slaying of a vampire heptad, seven powerful vampires living in a castle.. well.. anyway...
You could actually stake a vampire in combat with a wooden stake (or an arrow shaft). In order to do this, you first had to hit the vampire (-4 penalty if you don't have the Wooden Stake exotic weapon proficiency). If you hit, you must succeed in an opposed strength roll. If you succeed, the vampire is staked and is paralyzed.
Now, however, any of the other vampires could easily remove the stake, thereby enabling the staked vampire. The characteres had to decapacitate the vampire's head (coup de grace), and fill it with garlic OR pour holy water into the head.
If they killed a vampire without the stake - decapacitation - holy water thingy, they only turned gaseous and escaped to their coffins.
Thats my take on it.. I can see the point for those who dislike Buffy that you can actually stake them in combat, but I guarantee you, to first hit a vampire with a -4 weapon, and then suceeding an opposed strength roll.. its not easy..
Hope this will be of any help
