My Cleric was turned into a Vampire..

[taltamir]

OP: This might help you and your DM clarify things - the following is a direct excerpt from the EbCS on Alignment (pg 8)

"Alignments are relative gauges of a character or creature’s viewpoint, and not absolute barometers of affiliation and action; nothing is exactly as it seems. Alignments are blurred, so that it’s possible to encounter an evil silver dragon or a good vampire."

Which IMO trumps any other source book on the matter. Basically if you read the intro bit in the Eberron Campaign Setting you'll see that they have taken some liberty with the general rules "bending" them as they see fit for this particular campaign setting.

other sources never said you couldn't encounter a good vampire... merely that the process of becoming one turned you evil, after which you MAY turn good again.
Of course, this relies on two things:
1. the vampire entry says its always evil
2. the monster manual says that an acquired template of always evil is one for which the transformation changes your alignment, afterwards the alignment may change back...

the thing is, the eberron setting contradicts point 1. but point 1 was never EXACTLY in effect anyways because "always evil" meant "always become evil when first transform and may change alignment later".

Hence why it is really up to the DM / players. (well, it always was up to them anyways).

As for drinking blood, I am pretty sure there is a ring that makes you immune to sunlight AND never need to actually drink blood. (like a ring of sustenance + sunlight protection for vampires). just toss away your ring of sustenance and get one of those instead.

Also, I am totally uncertain on whether animal blood will suffice or not. An interesting twist would be if animal blood DOES suffice.. because that means that vampires are being hunted down like monsters, yet they eat animals just like humans do (a human may choose to eat other humans)... then you will really need to take craft (emo poetry) :P