Sleep and spinning down hard drives

Whenever I put my computer to sleep I hear the secondary drive (not the boot drive) spin down, and then the chassis power led starts blinking like it's supposed to when in S3 sleep mode. At this point in time I expect power to go off, i.e. fans stop spinning, signifying a complete transition to S3 sleep mode. However, the fans stay on and a couple seconds later, I see some activity on the boot drive and at the same time, the secondary drive spins up again. I assume there is some activity on the secondary drive as well which is what triggered it to spin back up; I can't tell for sure because I don't have an activity light hooked up to the secondary drive. Finally after a few more seconds, everything powers down. And just to note, the secondary drive does not spin down this time around before power is removed.

On the exact same system, I don't recall the extra secondary drive spin up happening under XP when putting the system to sleep, so I'm wondering why the secondary drive is spinning back up again before finally powering down? It seems that Windows 7 is doing some extra writes/reads to the drives, even after putting the system to sleep but before removing power. Any details on the sequence of events Windows 7 goes through when putting a system to Sleep?

One other thing to note is that the secondary drive is behind a RAID controller, so I suppose there is a possibility the RAID controller is spinning the secondary drive up again, but that seems unlikely since this behavior was not present with Win XP.

EDIT: I'm running Windows 7 Pro RTM

Some more info:
I noticed in the event log, AFTER the Kernel-Power "The system is entering sleep" event, there are 2 more events, both posted by the Service Control Manager regarding "The TCP/IP NetBIOS Helper service". It was sent a stop control and subsequently stopped. Would stopping The TCP/IP NetBIOS Helper service cause disk access? If so, why even bother spinning down the drives first? Or, why not stop the service BEFORE putting the system to sleep? Again, assuming it is stopping The TCP/IP NetBIOS Helper service is what's causing disk access.