Re: Clean environment
It doesn't matter how well-coded your OS is (and being Microsoft, it won't be THAT well coded). Keep starting programs, ending programs, saving state, reloading state, starting more programs, ending more programs, shuffling data into and out of memory, day after day after day...
It'll happen. Slowly perhaps, but out of those gazillions of operations you're asking the OS to do, SOME of them will bugger up. Sure, you might not notice it at first.. it'll just be having to click on an icon twice instead of once. However, slowly but surely, entropy will build up. Things will break. Stuff will slow down. Eventually, and I've seen it happen so many times on so many Windows machines of every version, you'll be flying along in some application or game, and *CRASH*. It's not a virus, it's not malware outside of maybe Microsoft's shitty DRM being tripped, it's just a simple consequence of thinking you can keep going forever on an OS that is not totally and utterly bug-free.
That's why it's nice to reboot every now and then. But hey, it's your machine. You do what you like with it. Go ahead and waste electricity by leaving the thing on. After all, it's your electricity bill. But don't accuse me, or anybody else, of being somehow inferior because we like to cold-reboot sometimes and make sure the OS has started up cleanly. Or perhaps we just don't want to burn through the MTBF of the various components for no good reason other than not being bothered with a power switch. Or, maybe, we don't want to die in a fire caused by an exploding power supply?
Of course, you can do all of the above if you like. I could care less.