Rep Points and Rep Power are confusing with the names being similiar.
You get 1 Rep Power for every 100 posts.
The number of green boxes under your avatar is a representation to everyone, how many rep points you have.
Of course you can check your own rep points in your user cp but you can't look in anyone else's, hence the little green boxes.
You also gain Rep Power from time spent here. If you look around, you'll see people that haven't posted in ages or don't have too many posts but they have good Rep Power level...look at the date they joined, in this case it's ususally a member from early on in CS.com
I like the rep system personally, it's not a popularity contest it simply shows everyone who has a good reputation in our community.