Hiren's Boot CD - HDD Diagnostics

I have a bunch of hard drives which I want to sell, so am wiping them using Hiren's Boot CD. I want to check that the drives are healthy first. Can anyone recommend a tool for this? There are several manufacturer ones on there, but are they specific to that brand?

What should I be looking out for? Is it the SMART monitoring?

Also, how do I access them from the disk on bootup?

Thanks!

I recommend using MHDD 4.6 (Also does mechanical check) or SmartUDM 2.00. If your drives support SMART, then you should be able to read their state from either of these programs. The should be in DOS tools, under Hard Disk Tools.

EDIT: And yes, most brand-specific tools will only work with their own branded hardware.