Windows 7: What is windows doing at 5am? and how do I stop it?

I'm trying to quiet down my PC. The primary hard drive is a loud maxtor, and the secondary is a quiet Samsung Spinpoint F1. I use it as a Windows Media Center, so it's on all night, but usually - even when in use - the primary drive hardly gets used. Until about 5am when I get woken up by constant hard disc access. It's not recording TV, it should be doing nothing - so what is it doing? How do I stop it?

perhaps you have a scheduled task going on or an auto defrag is happening

Not sure how to see scheduled tasks... but it's pretty much a clean install

Start, type in task, select Task Manager from the list.

That just shows the tasks unning, not any scheduled to run; and if they're running now, and the hard disc is not being accessed, that *should* rule them out as the problem.

Here's a screenshot of taskmanager as it is currently (and should always be)

Ok, I think it was the deragment. It was scheduled to run every wednesday from midnight (i.e. last night).
Strange though that "scheduled tasks" doesn't mention it - it's only in the defrag program. Thanks for the help guys.

Sorry, meant Task Scheduler.