It's worth pointing out that the concept of the True Vampire is seated in Christian lore. According to the original concept, a True Vampire is a fallen human. Dracula was described as "he is to mortal men what Lucifer is to angels, and his spawn are to us what demons are to angels".
The implication being that humans can 'fall' just as angels can, and in doing so, they become True Vampires.
This is reflected in the creation of genesis vampires (vampires that were not bitten by another, but became vampires on their own). Dracula became what he was because he blasphemed against God, damning the church, God, and all that they stood for.
That action was also mirrored in Hellsing, when Dracula chose to sell his soul and endure on in a mockery of life, rather than face the penalty for his sins.
This is further reinforced by the ending of Dracula, which has him praying to God to forgive him for turning his back on the light (the ending implies that he was forgiven, as he claimed to "see the gates [of heaven]" as he died).
Just a little FYI. Negima!vampires seem to be based on some sort of magical curse, rather than sin or spiritual corruption, so that's one major difference right there.