I have to say, in my experience, DRG is right about the porn thing. It gives off WAAAAAAAAY unrealistic expectations - especially for the inexperienced or uninitiated. I'm a advocate of porn but by no means do I think I should either try fuck like a pornstar or expect a woman to do the same. If you want that kind of girl, fine - just don't expect too much cuddling and kissing. You will likely get to share a lot of feelings - mostly hers as she tells you about her fucked up life. It can be quite depressing. If you are lucky enough to meet someone who you are compatible with on more than one level, then you're pretty lucky.
It's like anything associated with "wild living" - it can severely and detrimentally affect your enjoyment levels of just about every other thing in your life. If there was one thing I could change about my life, it'd be that!
But on the plus side - if you can objectify what you're watching and if it's just -*ahem*- a 'means to an end'
, then it probably won't do you too much harm. Plus, how much is too much?