How to turn on write protect on hard drive?

[Connor]

I'm playing around with the ideal of putting my hard drive in a clean condition and then turning on the "write protect" for the hard drive to eliminate spyware, trojans and virus's from downloading to it. I'll then be using a usb pen drive to do all my on line work.

Has anyone heard of doing this? I know a lot of severs are set up this way for the protection it affords. If you have any help as to how to turn on the "write protect" for the HD in my Thinkpad r40, please let me know.

Thanks...

Connor