The best way to ground yourself when working on the internals of a pc is to touch the metal case inside first. It will not damage the components inside if you do this. I build computers on a weekly basis, and I use a grounding bracelet. That being said, when I go to someones house to fix their PC I never use the grounding wire, simply the metal case inside to discharge any static electricity.
I've been doing this for 15 years as well without incident.
As per the magnetic screwdriver, I have used them, there is never really a need to put it close enought to the HD to damage it, unless of course you are installing it. I have installed HD's with a magnetic screwdriver and have never had incident, but I may have been just lucky.
Any A+ book is good for info like this as Invictus said.