FWIW, I keep mine on 24/7. I suppose there's good arguments on both sides,
but based on my experiences and frankly gut feelings, I think it's better to
keep things running at a constant temp/humidity, to the extent possible.
But the problem today goes beyond just the issue of hardware.
NOT running 24/7 these days is, for many of us, simply impractical. I
literally have dozens of background jobs I need to run nightly, but the idea
of running them during the day would be a real hassle and drag on my
resources. I run a FULL virus scan twice a week (this alone takes a couple
hours), plus nighly signature updates. Add to this spyware scans (at least
three), my backup jobs, Outlook Express newsgroup updates (so I don't miss
messages should I not use the app for a few days), RAID synchronization
checks, Microsoft updates, various other apps that like to auto-update,
webpage monitoring apps ("watchers"), podcast updates, DL jobs, instant
messengers (suppose someone wants to reach you at an odd hour, or leave a
message), remote access needs, Tivo Desktop (this utility makes my networked
MPEGs, mp3, etc., available to my three Tivo's at anytime of day), and on
and on.
IOW, my machines are *working* 24/7, even when I'm not personally in front
of them! While not everyone may require as many jobs as I do, I don't think
it's all that hard for any system to require/profit from 'round the clock
operations. It's just too much hassle to expect to have these jobs running
during daily operating hours, or worse, requiring me to remember to boot the
machine so they can. IMO, for anyone who uses their computer for more than
a simple email check, or browse a few websites, the days of running a few
hours and shutting down are over. And it will only get worse as people
employ their computers for more and more purposes, esp. network enabled apps
(the network never closes, even if you do!).
Jim