http://www.straightdope.com/classics/a990507.html
In the above column and others like it (the one on Dracula) there was speculation on vamps. There’s a great book on the subject called Vampires, Burial, & Death, by Paul Barber. It’s a historical look at vampires, and the mentality that surounded the idea death and burial at the time when vampire folklore was prevelant. It’s a good read, at any rate.