hard to say really, depends on how much your energy company charges you for electricty, plus we dont actually know how much energy your comp is consuming.
I turn the monitor off when not in use With the PC, I think most have pretty good power management these days ...
I used to only leave it on when downloading and now that when im not downloading, i still leave it on..stupid habit
I would turn my screensaver on but on some apps it lets the screensaver override the app and i have to move the mouse everytime So i dont use SS or auto shut monitor
lol. its not that good either, the power supply doesn't like the strain of it that much, if on u also mean standby thats not too bad, but a computer likes a full shutdown once in a while
My room get's really hot if I keep it on all the time, so I have to let it cool down and really does make a lot of noise keeps me awake at night.
actually oregon is not that how. hottest day in summer is like 100 F, and thats like 1 or 2 days out of the whole summer
i leave it on for dls and but when im at dorm, its on 24/7. and my pc is just fine howerver i did had to rma my mobo b4 :X
I leave 2 of my computers on 24/7. They go through occasional reboots, but rarely do they stay off. No problems with hardware failures.