>Google finds tons of programs that supposedly will check my hard drive for physical "health". But I am not ready to trust these off the bad. Has anybody personally used a program that actually did check the drive (and didn't format it - concern I have <g>) and was helpful?

In addition to Sergey's recommendation about manufacturer-specific diagnostic utilities, you can enable the HD S.M.A.R.T. function on your motherboard: http://en.wikipedia.org/wiki/S.M.A.R.T. In practice, this is semi-useful

One truly excellent utility I've used a number of times is SpinRite: http://www.grc.com/sr/spinrite.htm

It can thoroughly test a drive for bad sectors and map them out, moving data that may be contained in them if necessary. You can use it periodically for drive maintenance, or for data recovery if a drive starts to fail.