I use "Sleep" a lot because it uses a couple watts more than just turning your PC off. I will do a quick test right now just to make sure (I have a Kill A Watt meter).
System "Off": 4 watts
System "Sleep": 3~4 watts!!! Hmm... maybe I should test that again...
System included in signature - did NOT include the monitor but included KB, mouse, and network cable plugged into LAN connection.