I'd like to reduce power use and general wear and tear on my main PC, but don't fully understand what the various settings do.

I've got WinXP Pro SP1 on this machine, with 2 hard drives.

What would be the best settings, given that: the PC is on for around 18 hours per day - during that time it's used for about 12 hours. The times between use are random ie range from anything like 10 minutes an hour to a couple of hours of inactivity.

At the moment the only setting is for monitor to go to sleep after 20 minutes. I've heard that hibernation isn't a good option for desktops - quote Godfather as I recall. (although hibernation seems to be working great for my new laptop)