SATA is IDE, its just Serial versus Parallel. From my experience, if you are not using raid then you do not need to F6 and install Raid drivers (Built 6 machines here at work with SATA drives but not in raid format! Go figure!)

As far as your memory count, there is always some memory reserved by either AGP Window, or Shadowing (My Asus boards count everything then subtract the AGP window and any other "Shared" memory holes from the total count.