WD External Harddrive on/off question

Unfortunatly most don't come with a switch, it's probably a safeguard to prevent you turning it off before it's finished. However once it's been safely ejected the spinning should stop shortly. Are you removing the usb cable when finished? that should shut if off, my My Book does.

Well, I just read a little bit off another site and some people think it's better just to leave the drive running whenever the computer is on. I thought it would be better for the hard drive to only run when you actually need it and it wouldn't have as much wear and tear this way. But I read that it's better to run all the time than to just start up and heat up and then instantly cool down. So I don't know. I had a MyBook about two years ago and I would only plug it in when I needed it and then take out the USB when I was done and it died pretty quick so I hesitated for a while to get another external hard drive. But with the first one I never unmounted it, instead I just yanked out the USB from my laptop, so that might have had something to do with it  

I guess I will just let it run the whole time the computer is on and see how it goes...

So what do you guys think? Leave a hard drive on while the computer is on and treat it like an internal drive, or only have it on when you need it or are using it?

I use a My book and an Elements, both are over two years old now and dont have any issues. I use the eject function, as soon as it says safe to remove I remove.
I have never bothered about the spinning, maybe the heads have been parked once its ejected so the spinning doesnt matter?

Regardless of if it is better to leave it running or not (wear and tear wise) due to your intended use of it I would say at minimum you should unplug it form the computer anyhow. If it is attached to the computer and on and a destructive virus hits your machine, then the backup drive is also at risk and becomes useless.