i have been the victim of several hard drive failures recently so i wish to have an extra drive in my box to backup important info. Is there a way to make it so this drive is not always running but can be used when NEEDED?

i run windows xp pro What about an External Hard Drive?

In fact, if you suspect your hard drive will fail soon, I would get a new one immediately.the old drive was under warranty but i could not wait that long for it to COME through the mail so i purchased a new drive and got my system running again. now i have the replacement drive here and was going to install it as a backup only drive. i was WONDERING if there was a way to have it in the system but only running when i needed it.

I'm not sure, but I don't see the harm in leaving it on as a slave.Probably the easiest and SAFEST way to use that extra drive would be in an external enclosure. They can be had for about $30 and that would allow you to have it plugged in and running ONLY when you need to write to it.
You can't just turn an internal drive on and off at will.
You CAN however set the drives to POWER DOWN in just a few minutes of inactivity, by setting the shutdown time in "Power Management" in your control panel.
I set mine to power-down after ten minutes of inactivity. That saves power and creates less heat inside of the PC.

Most backup programs will write to an external USB drive.

Good luck to you!

The Shadow