Ahh... the werewolf/ vampire thing. Ever play or heard of Morrowind? You can get this vampires disease and become a super strong character, but have to travel by night and no one talks to you. You can always this cured.
One of the expansions for Morrowind, Bloodmoon, you can become a werewolf... I don\'t know how being a werewolf works in that game.
So yeah a being a vampire should make you stronger, but sunlight should like, kill you!