@Rezident
Vampires gave me my first righteous kicking when I encountered them too, they still do sometimes if I let my guard down. I don't know that this game really caters for playing a pure class archetype, it would be quite easy if you mixed in some magic.
With good enough blades and skills (15x backstab, some means of combat disengaging like the stealth-crouch or pacify or invisibility) you can take them out quickly without much trouble.
Are there poisons that can paralyze (I don't really use poisons, but this is essentially the rogue equivalent of magic in the game)? If so, you might want to try carrying some of that around, a decent paralyze will let you cut a vampire up whilst it lays helpless on the floor. A Turn Undead (undead fear spell) based poison should make them easy pickings so long as they don't run like headless chickens into their buddies.
The other thing is to boost up your magic resistances. Sacrifice your +armor and +damage boosts for these when fighting a caster, like there are necklaces sold on merchants that give 70% fire resistance. Vamps can be a bit violent in melee but mostly they're a pain because of their bloodsucking/lifedrains and spells.
At 45 if they're kicking your tail, it's going to be an equipment deficiency along these lines. Be sure to scour merchants on every sell-up for any apparel that may be situationally useful (especially if it's lightweight) and buy it to lug around or buy it to disenchant so you can make your own.
One thing I do NOT bother with is magicka sapping weapons, just doesn't seem worth the hassle.
I use daedric swords/daggers (at your level you should either be able to make these, or at least get and improve ebony ones which aren't far off), but they're plain and not enchanted since I've been lazy on that skill.
P.s. In fights against mages and dragons, I use the +resistances based dragon priest mask (Otar) too. Once you start collecting these, they can be very useful things to have at hand.
