Battery Usage

[justlaxin13]

I suppose this could just be a general Android question, but towards the end of a day of use with my SGSII i checked the battery usage info and found that "Android OS" and "Android System" were using 21% and 11% of the battery, respectively. What are those two things actually representative of the phone doing in terms of my usage? I only ask because I don't remember those generally being that high on my Captivate. (yes, i can get kinda neurotic about battery life, especially after my last phone...)