[CentOS] Minimising disk I/O

I'd like to get disk I/O down to a minimum for my new Centos 
5.5 installation.

The machine will not be used as a web server anymore, as 
that's now hosted on a cloud platform. So there are no HTTP 
requests coming down the line.

If I move the SWAP partition and /var/log/ to a small spare 
drive, and install Centos on the new larger drive, is there 
anything else that would cause disk activity on the main 
drive, when the machine is running but not in use?

fetchmail will be collecting my email hourly, but I'd like 
the drive to spin down and go into hibernate mode if 
possible.

I have a backup drive that gets woken up once an hour to 
backup email, and also during the night to make backups 
of specified directories every 24 hours.

Apart from that, the drive is not in use, unless I run a 
backup script manually.

So I'm hoping to do the same for the main drive if that's 
posible?

Kind Regards,

Keith Roberts

-- 
In theory, theory and practice are the same;
in practice they are not.

This email was sent from my laptop with Centos 5.5