VN means visual novel, I can't be bothered to explain what they are so here's a youtube video of the F/SN VN prologue:
http://www.youtube.com/watch?v=BA-3vWjVvs8
Anyway, they're usually better than the anime in the way that books are better than movies and tv adaptations. If you're interested go here:
http://www.animetake.com/forums/gami...vel-links.html
Look for Fate Stay Night and download the megaupload links. Then follow the instructions on the main post to change your locale to Japanese before playing. If you have any questions feel free to message me.
Oh yes, I forgot. The visual novel does contain a few sex scenes here and there. If that bothers you then stay away.