old testament

I have a hard time reading the Old Testament. I like to pick and choose what I read, the good stories like Genesis and Exodus, Job, Daniel, and Ruth, and of course Psalms and Proverbs. I've been reading 1, 2 Samuel lately, and remembering why I have such a hard time reading this stuff. I am so confused about how everyone kills people. Seriously, in what I read today in 2 Sam 7 like thousands and thousands of people died. Why, why is that necessary and what good did it do, and where did God fit in? I know life was different then, living under the Law, but what's with all the needless killing? At times I think it would have been awesome to live back then and see all of the huge miracles and hear God speak to you so loud and clear. But I am glad to be living in grace, miracles still happen, God still speaks, and the crazy kill everyone sprees are fewer and far between. But seriously, can anyone shed some light on the territorial killing sprees of the Old Testament? What are we supposed to take from that, what do we learn about God's character or how to do life from that? Right now all I feel is sad for all the kids whose parents died and were orphaned.