legend is indeed one of the inspirations for "Hostel", along with sundry urban legends and folktales.

It's debatable as to how many Countess Bathory actually killed - estimates range from slightly under 100 to over 600. Personally, I'm not quite sold on the "bathing in the blood of virgins" thing. From what I've read, she strikes me more as a sadist who most likely received some form of sexual gratification out of killing people - somewhat along the lines of Gilles de Rais.

At the very least, she was most certainly a serial killer.