What spider is VERY small, furry, and fast that lives in the home in Ohio?

I was just messing with my computer a minute ago, and for what seems like the twentieth time today, a small black spider crawled really fast across the screen. It doesn't seem aggresive, because I kinda just flick it away and it doesn't get angry. It's about a centimeter wide... maybe less.Like I said... VERY small. Looks furry. I just wanted to know what it might be and/or if I should kill it or let it be. I am not afraid of spiders, but I don't want to get bit by one that is poisonous. Any comments would help. By the way... I live in southern Ohio, if that helps any.